* [PATCH net-next] r8169: make use of xmit_more
@ 2019-07-28 9:25 Heiner Kallweit
2019-07-29 18:05 ` David Miller
2019-08-08 14:37 ` Holger Hoffstätte
0 siblings, 2 replies; 13+ messages in thread
From: Heiner Kallweit @ 2019-07-28 9:25 UTC (permalink / raw)
To: Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
There was a previous attempt to use xmit_more, but the change had to be
reverted because under load sometimes a transmit timeout occurred [0].
Maybe this was caused by a missing memory barrier, the new attempt
keeps the memory barrier before the call to netif_stop_queue like it
is used by the driver as of today. The new attempt also changes the
order of some calls as suggested by Eric.
[0] https://lkml.org/lkml/2019/2/10/39
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
drivers/net/ethernet/realtek/r8169_main.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 864ca529d..d9261e68f 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -5637,6 +5637,8 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
struct device *d = tp_to_dev(tp);
dma_addr_t mapping;
u32 opts[2], len;
+ bool stop_queue;
+ bool door_bell;
int frags;
if (unlikely(!rtl_tx_slots_avail(tp, skb_shinfo(skb)->nr_frags))) {
@@ -5680,13 +5682,13 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
txd->opts2 = cpu_to_le32(opts[1]);
- netdev_sent_queue(dev, skb->len);
-
skb_tx_timestamp(skb);
/* Force memory writes to complete before releasing descriptor */
dma_wmb();
+ door_bell = __netdev_sent_queue(dev, skb->len, netdev_xmit_more());
+
txd->opts1 = rtl8169_get_txd_opts1(opts[0], len, entry);
/* Force all memory writes to complete before notifying device */
@@ -5694,14 +5696,19 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
tp->cur_tx += frags + 1;
- RTL_W8(tp, TxPoll, NPQ);
-
- if (!rtl_tx_slots_avail(tp, MAX_SKB_FRAGS)) {
+ stop_queue = !rtl_tx_slots_avail(tp, MAX_SKB_FRAGS);
+ if (unlikely(stop_queue)) {
/* Avoid wrongly optimistic queue wake-up: rtl_tx thread must
* not miss a ring update when it notices a stopped queue.
*/
smp_wmb();
netif_stop_queue(dev);
+ }
+
+ if (door_bell)
+ RTL_W8(tp, TxPoll, NPQ);
+
+ if (unlikely(stop_queue)) {
/* Sync with rtl_tx:
* - publish queue status and cur_tx ring index (write barrier)
* - refresh dirty_tx ring index (read barrier).
--
2.22.0
^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-07-28 9:25 [PATCH net-next] r8169: make use of xmit_more Heiner Kallweit
@ 2019-07-29 18:05 ` David Miller
2019-08-08 14:37 ` Holger Hoffstätte
1 sibling, 0 replies; 13+ messages in thread
From: David Miller @ 2019-07-29 18:05 UTC (permalink / raw)
To: hkallweit1; +Cc: nic_swsd, netdev, linux, edumazet
From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Sun, 28 Jul 2019 11:25:19 +0200
> There was a previous attempt to use xmit_more, but the change had to be
> reverted because under load sometimes a transmit timeout occurred [0].
> Maybe this was caused by a missing memory barrier, the new attempt
> keeps the memory barrier before the call to netif_stop_queue like it
> is used by the driver as of today. The new attempt also changes the
> order of some calls as suggested by Eric.
>
> [0] https://lkml.org/lkml/2019/2/10/39
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-07-28 9:25 [PATCH net-next] r8169: make use of xmit_more Heiner Kallweit
2019-07-29 18:05 ` David Miller
@ 2019-08-08 14:37 ` Holger Hoffstätte
2019-08-08 15:53 ` Holger Hoffstätte
1 sibling, 1 reply; 13+ messages in thread
From: Holger Hoffstätte @ 2019-08-08 14:37 UTC (permalink / raw)
To: Heiner Kallweit, Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
Hello Heiner -
On 7/28/19 11:25 AM, Heiner Kallweit wrote:
> There was a previous attempt to use xmit_more, but the change had to be
> reverted because under load sometimes a transmit timeout occurred [0].
> Maybe this was caused by a missing memory barrier, the new attempt
> keeps the memory barrier before the call to netif_stop_queue like it
> is used by the driver as of today. The new attempt also changes the
> order of some calls as suggested by Eric.
>
> [0] https://lkml.org/lkml/2019/2/10/39
>
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
I decided to take one for the team and merged this into my 5.2.x tree (just
fixing up the path) and it has been working fine for the last 2 weeks in two
machines..until today, when for the first time in forever some random NFS traffic
made this old friend come out from under the couch:
[Aug 8 14:13] ------------[ cut here ]------------
[ +0.000006] NETDEV WATCHDOG: eth0 (r8169): transmit queue 0 timed out
[ +0.000021] WARNING: CPU: 3 PID: 0 at net/sched/sch_generic.c:442 dev_watchdog+0x21f/0x230
[ +0.000001] Modules linked in: lz4 lz4_compress lz4_decompress nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel btrfs xor zstd_compress raid6_pq zstd_decompress bfq jitterentropy_rng nct6775 hwmon_vid coretemp hwmon x86_pkg_temp_thermal aesni_intel aes_x86_64 i915 glue_helper crypto_simd cryptd i2c_i801 intel_gtt i2c_algo_bit iosf_mbi drm_kms_helper syscopyarea usbhid sysfillrect r8169 sysimgblt fb_sys_fops realtek drm libphy drm_panel_orientation_quirks i2c_core video backlight mq_deadline
[ +0.000026] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.2.7 #1
[ +0.000001] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
[ +0.000004] RIP: 0010:dev_watchdog+0x21f/0x230
[ +0.000002] Code: 3b 00 75 ea eb ad 4c 89 ef c6 05 1c 45 bd 00 01 e8 66 35 fc ff 44 89 e1 4c 89 ee 48 c7 c7 e8 5e fc 81 48 89 c2 e8 90 df 92 ff <0f> 0b eb 8e 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 66 66 66 66 90
[ +0.000002] RSP: 0018:ffffc90000118e68 EFLAGS: 00010286
[ +0.000002] RAX: 0000000000000000 RBX: ffff8887f7837600 RCX: 0000000000000303
[ +0.000001] RDX: 0000000000000001 RSI: 0000000000000092 RDI: ffffffff827a488c
[ +0.000001] RBP: ffff8887f9fbc440 R08: 0000000000000303 R09: 0000000000000003
[ +0.000001] R10: 000000000001004c R11: 0000000000000001 R12: 0000000000000000
[ +0.000009] R13: ffff8887f9fbc000 R14: ffffffff8173aa20 R15: dead000000000200
[ +0.000001] FS: 0000000000000000(0000) GS:ffff8887ff580000(0000) knlGS:0000000000000000
[ +0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ +0.000001] CR2: 00007f8d1c04d000 CR3: 0000000002209001 CR4: 00000000000606e0
[ +0.000000] Call Trace:
[ +0.000002] <IRQ>
[ +0.000005] call_timer_fn+0x2b/0x120
[ +0.000002] expire_timers+0xa4/0x100
[ +0.000001] run_timer_softirq+0x8c/0x170
[ +0.000002] ? __hrtimer_run_queues+0x13a/0x290
[ +0.000003] ? sched_clock_cpu+0xe/0x130
[ +0.000003] __do_softirq+0xeb/0x2de
[ +0.000003] irq_exit+0x9d/0xe0
[ +0.000002] smp_apic_timer_interrupt+0x60/0x110
[ +0.000003] apic_timer_interrupt+0xf/0x20
[ +0.000001] </IRQ>
[ +0.000003] RIP: 0010:cpuidle_enter_state+0xad/0x930
[ +0.000001] Code: c5 66 66 66 66 90 31 ff e8 90 99 9e ff 80 7c 24 0b 00 74 12 9c 58 f6 c4 02 0f 85 39 08 00 00 31 ff e8 e7 26 a2 ff fb 45 85 e4 <0f> 88 34 02 00 00 49 63 cc 4c 2b 2c 24 48 8d 04 49 48 c1 e0 05 8b
[ +0.000000] RSP: 0018:ffffc9000008be50 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
[ +0.000001] RAX: ffff8887ff5a9180 RBX: ffffffff822b6c40 RCX: 000000000000001f
[ +0.000001] RDX: 0000000000000000 RSI: 0000000033087154 RDI: 0000000000000000
[ +0.000001] RBP: ffff8887ff5b1310 R08: 000030d021fae397 R09: ffff8887ff59c8c0
[ +0.000000] R10: ffff8887ff59c8c0 R11: 0000000000000006 R12: 0000000000000004
[ +0.000001] R13: 000030d021fae397 R14: 0000000000000004 R15: ffff8887fc281600
[ +0.000001] cpuidle_enter+0x29/0x40
[ +0.000002] do_idle+0x1e5/0x280
[ +0.000001] cpu_startup_entry+0x19/0x20
[ +0.000002] start_secondary+0x186/0x1c0
[ +0.000001] secondary_startup_64+0xa4/0xb0
[ +0.000001] ---[ end trace 99493c768580f4fd ]---
The device is:
Aug 7 23:19:09 tux kernel: libphy: r8169: probed
Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: RTL8168evl/8111evl, c8:60:00:68:33:cc, XID 2c9, IRQ 36
Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
Aug 7 23:19:12 tux kernel: RTL8211E Gigabit Ethernet r8169-400:00: attached PHY driver [RTL8211E Gigabit Ethernet] (mii_bus:phy_addr=r8169-400:00, irq=IGNORE)
Aug 7 23:19:13 tux kernel: r8169 0000:04:00.0 eth0: No native access to PCI extended config space, falling back to CSI
and using fq_codel, of course.
This cpuidle hiccup used to be completely gone without xmit_more and this was
the first (and so far only) time since merging it (regardless of load).
Also, while I'm using BMQ as CPU scheduler, that hasn't made a difference for
this particular problem in the past (with MuQSS/PDS) either; way back when I had
Eric's previous attempt(s) it also hiccupped with CFS.
Revert or wait for more reports when -next is merged in 5.4?
thanks,
Holger
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-08 14:37 ` Holger Hoffstätte
@ 2019-08-08 15:53 ` Holger Hoffstätte
2019-08-08 18:17 ` Heiner Kallweit
0 siblings, 1 reply; 13+ messages in thread
From: Holger Hoffstätte @ 2019-08-08 15:53 UTC (permalink / raw)
To: Heiner Kallweit, Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
On 8/8/19 4:37 PM, Holger Hoffstätte wrote:
>
> Hello Heiner -
>
> On 7/28/19 11:25 AM, Heiner Kallweit wrote:
>> There was a previous attempt to use xmit_more, but the change had to be
>> reverted because under load sometimes a transmit timeout occurred [0].
>> Maybe this was caused by a missing memory barrier, the new attempt
>> keeps the memory barrier before the call to netif_stop_queue like it
>> is used by the driver as of today. The new attempt also changes the
>> order of some calls as suggested by Eric.
>>
>> [0] https://lkml.org/lkml/2019/2/10/39
>>
>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>
> I decided to take one for the team and merged this into my 5.2.x tree (just
> fixing up the path) and it has been working fine for the last 2 weeks in two
> machines..until today, when for the first time in forever some random NFS traffic
> made this old friend come out from under the couch:
>
> [Aug 8 14:13] ------------[ cut here ]------------
> [ +0.000006] NETDEV WATCHDOG: eth0 (r8169): transmit queue 0 timed out
> [ +0.000021] WARNING: CPU: 3 PID: 0 at net/sched/sch_generic.c:442 dev_watchdog+0x21f/0x230
> [ +0.000001] Modules linked in: lz4 lz4_compress lz4_decompress nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel btrfs xor zstd_compress raid6_pq zstd_decompress bfq jitterentropy_rng nct6775 hwmon_vid coretemp hwmon x86_pkg_temp_thermal aesni_intel aes_x86_64 i915 glue_helper crypto_simd cryptd i2c_i801 intel_gtt i2c_algo_bit iosf_mbi drm_kms_helper syscopyarea usbhid sysfillrect r8169 sysimgblt fb_sys_fops realtek drm libphy drm_panel_orientation_quirks i2c_core video backlight mq_deadline
> [ +0.000026] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.2.7 #1
> [ +0.000001] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
> [ +0.000004] RIP: 0010:dev_watchdog+0x21f/0x230
> [ +0.000002] Code: 3b 00 75 ea eb ad 4c 89 ef c6 05 1c 45 bd 00 01 e8 66 35 fc ff 44 89 e1 4c 89 ee 48 c7 c7 e8 5e fc 81 48 89 c2 e8 90 df 92 ff <0f> 0b eb 8e 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 66 66 66 66 90
> [ +0.000002] RSP: 0018:ffffc90000118e68 EFLAGS: 00010286
> [ +0.000002] RAX: 0000000000000000 RBX: ffff8887f7837600 RCX: 0000000000000303
> [ +0.000001] RDX: 0000000000000001 RSI: 0000000000000092 RDI: ffffffff827a488c
> [ +0.000001] RBP: ffff8887f9fbc440 R08: 0000000000000303 R09: 0000000000000003
> [ +0.000001] R10: 000000000001004c R11: 0000000000000001 R12: 0000000000000000
> [ +0.000009] R13: ffff8887f9fbc000 R14: ffffffff8173aa20 R15: dead000000000200
> [ +0.000001] FS: 0000000000000000(0000) GS:ffff8887ff580000(0000) knlGS:0000000000000000
> [ +0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ +0.000001] CR2: 00007f8d1c04d000 CR3: 0000000002209001 CR4: 00000000000606e0
> [ +0.000000] Call Trace:
> [ +0.000002] <IRQ>
> [ +0.000005] call_timer_fn+0x2b/0x120
> [ +0.000002] expire_timers+0xa4/0x100
> [ +0.000001] run_timer_softirq+0x8c/0x170
> [ +0.000002] ? __hrtimer_run_queues+0x13a/0x290
> [ +0.000003] ? sched_clock_cpu+0xe/0x130
> [ +0.000003] __do_softirq+0xeb/0x2de
> [ +0.000003] irq_exit+0x9d/0xe0
> [ +0.000002] smp_apic_timer_interrupt+0x60/0x110
> [ +0.000003] apic_timer_interrupt+0xf/0x20
> [ +0.000001] </IRQ>
> [ +0.000003] RIP: 0010:cpuidle_enter_state+0xad/0x930
> [ +0.000001] Code: c5 66 66 66 66 90 31 ff e8 90 99 9e ff 80 7c 24 0b 00 74 12 9c 58 f6 c4 02 0f 85 39 08 00 00 31 ff e8 e7 26 a2 ff fb 45 85 e4 <0f> 88 34 02 00 00 49 63 cc 4c 2b 2c 24 48 8d 04 49 48 c1 e0 05 8b
> [ +0.000000] RSP: 0018:ffffc9000008be50 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
> [ +0.000001] RAX: ffff8887ff5a9180 RBX: ffffffff822b6c40 RCX: 000000000000001f
> [ +0.000001] RDX: 0000000000000000 RSI: 0000000033087154 RDI: 0000000000000000
> [ +0.000001] RBP: ffff8887ff5b1310 R08: 000030d021fae397 R09: ffff8887ff59c8c0
> [ +0.000000] R10: ffff8887ff59c8c0 R11: 0000000000000006 R12: 0000000000000004
> [ +0.000001] R13: 000030d021fae397 R14: 0000000000000004 R15: ffff8887fc281600
> [ +0.000001] cpuidle_enter+0x29/0x40
> [ +0.000002] do_idle+0x1e5/0x280
> [ +0.000001] cpu_startup_entry+0x19/0x20
> [ +0.000002] start_secondary+0x186/0x1c0
> [ +0.000001] secondary_startup_64+0xa4/0xb0
> [ +0.000001] ---[ end trace 99493c768580f4fd ]---
>
> The device is:
>
> Aug 7 23:19:09 tux kernel: libphy: r8169: probed
> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: RTL8168evl/8111evl, c8:60:00:68:33:cc, XID 2c9, IRQ 36
> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
> Aug 7 23:19:12 tux kernel: RTL8211E Gigabit Ethernet r8169-400:00: attached PHY driver [RTL8211E Gigabit Ethernet] (mii_bus:phy_addr=r8169-400:00, irq=IGNORE)
> Aug 7 23:19:13 tux kernel: r8169 0000:04:00.0 eth0: No native access to PCI extended config space, falling back to CSI
>
> and using fq_codel, of course.
>
> This cpuidle hiccup used to be completely gone without xmit_more and this was
> the first (and so far only) time since merging it (regardless of load).
> Also, while I'm using BMQ as CPU scheduler, that hasn't made a difference for
> this particular problem in the past (with MuQSS/PDS) either; way back when I had
> Eric's previous attempt(s) it also hiccupped with CFS.
>
> Revert or wait for more reports when -next is merged in 5.4?
Another question/data point: I've had the whole basket of offloads activated:
ethtool --offload eth0 rx on tx on gro on gso on sg on tso on
and this caused zero problems without the xmit_more patch. However I just saw
that net-next has a patch where TSO is disabled due to a known HW defect in
RTL8168evl, which is of course what I have. Could this be the reason for the
stall/hiccup when xmit_more has its fingers in the pie? I kind of know what
xmit_more does, just not how it could interact with a possibly broken TSO that
nevertheless seems to work fine otherwise..
thanks
Holger
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-08 15:53 ` Holger Hoffstätte
@ 2019-08-08 18:17 ` Heiner Kallweit
2019-08-08 19:52 ` Holger Hoffstätte
0 siblings, 1 reply; 13+ messages in thread
From: Heiner Kallweit @ 2019-08-08 18:17 UTC (permalink / raw)
To: Holger Hoffstätte, Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
On 08.08.2019 17:53, Holger Hoffstätte wrote:
> On 8/8/19 4:37 PM, Holger Hoffstätte wrote:
>>
>> Hello Heiner -
>>
>> On 7/28/19 11:25 AM, Heiner Kallweit wrote:
>>> There was a previous attempt to use xmit_more, but the change had to be
>>> reverted because under load sometimes a transmit timeout occurred [0].
>>> Maybe this was caused by a missing memory barrier, the new attempt
>>> keeps the memory barrier before the call to netif_stop_queue like it
>>> is used by the driver as of today. The new attempt also changes the
>>> order of some calls as suggested by Eric.
>>>
>>> [0] https://lkml.org/lkml/2019/2/10/39
>>>
>>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>>
>> I decided to take one for the team and merged this into my 5.2.x tree (just
>> fixing up the path) and it has been working fine for the last 2 weeks in two
>> machines..until today, when for the first time in forever some random NFS traffic
>> made this old friend come out from under the couch:
>>
>> [Aug 8 14:13] ------------[ cut here ]------------
>> [ +0.000006] NETDEV WATCHDOG: eth0 (r8169): transmit queue 0 timed out
>> [ +0.000021] WARNING: CPU: 3 PID: 0 at net/sched/sch_generic.c:442 dev_watchdog+0x21f/0x230
>> [ +0.000001] Modules linked in: lz4 lz4_compress lz4_decompress nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel btrfs xor zstd_compress raid6_pq zstd_decompress bfq jitterentropy_rng nct6775 hwmon_vid coretemp hwmon x86_pkg_temp_thermal aesni_intel aes_x86_64 i915 glue_helper crypto_simd cryptd i2c_i801 intel_gtt i2c_algo_bit iosf_mbi drm_kms_helper syscopyarea usbhid sysfillrect r8169 sysimgblt fb_sys_fops realtek drm libphy drm_panel_orientation_quirks i2c_core video backlight mq_deadline
>> [ +0.000026] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.2.7 #1
>> [ +0.000001] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
>> [ +0.000004] RIP: 0010:dev_watchdog+0x21f/0x230
>> [ +0.000002] Code: 3b 00 75 ea eb ad 4c 89 ef c6 05 1c 45 bd 00 01 e8 66 35 fc ff 44 89 e1 4c 89 ee 48 c7 c7 e8 5e fc 81 48 89 c2 e8 90 df 92 ff <0f> 0b eb 8e 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 66 66 66 66 90
>> [ +0.000002] RSP: 0018:ffffc90000118e68 EFLAGS: 00010286
>> [ +0.000002] RAX: 0000000000000000 RBX: ffff8887f7837600 RCX: 0000000000000303
>> [ +0.000001] RDX: 0000000000000001 RSI: 0000000000000092 RDI: ffffffff827a488c
>> [ +0.000001] RBP: ffff8887f9fbc440 R08: 0000000000000303 R09: 0000000000000003
>> [ +0.000001] R10: 000000000001004c R11: 0000000000000001 R12: 0000000000000000
>> [ +0.000009] R13: ffff8887f9fbc000 R14: ffffffff8173aa20 R15: dead000000000200
>> [ +0.000001] FS: 0000000000000000(0000) GS:ffff8887ff580000(0000) knlGS:0000000000000000
>> [ +0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ +0.000001] CR2: 00007f8d1c04d000 CR3: 0000000002209001 CR4: 00000000000606e0
>> [ +0.000000] Call Trace:
>> [ +0.000002] <IRQ>
>> [ +0.000005] call_timer_fn+0x2b/0x120
>> [ +0.000002] expire_timers+0xa4/0x100
>> [ +0.000001] run_timer_softirq+0x8c/0x170
>> [ +0.000002] ? __hrtimer_run_queues+0x13a/0x290
>> [ +0.000003] ? sched_clock_cpu+0xe/0x130
>> [ +0.000003] __do_softirq+0xeb/0x2de
>> [ +0.000003] irq_exit+0x9d/0xe0
>> [ +0.000002] smp_apic_timer_interrupt+0x60/0x110
>> [ +0.000003] apic_timer_interrupt+0xf/0x20
>> [ +0.000001] </IRQ>
>> [ +0.000003] RIP: 0010:cpuidle_enter_state+0xad/0x930
>> [ +0.000001] Code: c5 66 66 66 66 90 31 ff e8 90 99 9e ff 80 7c 24 0b 00 74 12 9c 58 f6 c4 02 0f 85 39 08 00 00 31 ff e8 e7 26 a2 ff fb 45 85 e4 <0f> 88 34 02 00 00 49 63 cc 4c 2b 2c 24 48 8d 04 49 48 c1 e0 05 8b
>> [ +0.000000] RSP: 0018:ffffc9000008be50 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
>> [ +0.000001] RAX: ffff8887ff5a9180 RBX: ffffffff822b6c40 RCX: 000000000000001f
>> [ +0.000001] RDX: 0000000000000000 RSI: 0000000033087154 RDI: 0000000000000000
>> [ +0.000001] RBP: ffff8887ff5b1310 R08: 000030d021fae397 R09: ffff8887ff59c8c0
>> [ +0.000000] R10: ffff8887ff59c8c0 R11: 0000000000000006 R12: 0000000000000004
>> [ +0.000001] R13: 000030d021fae397 R14: 0000000000000004 R15: ffff8887fc281600
>> [ +0.000001] cpuidle_enter+0x29/0x40
>> [ +0.000002] do_idle+0x1e5/0x280
>> [ +0.000001] cpu_startup_entry+0x19/0x20
>> [ +0.000002] start_secondary+0x186/0x1c0
>> [ +0.000001] secondary_startup_64+0xa4/0xb0
>> [ +0.000001] ---[ end trace 99493c768580f4fd ]---
>>
>> The device is:
>>
>> Aug 7 23:19:09 tux kernel: libphy: r8169: probed
>> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: RTL8168evl/8111evl, c8:60:00:68:33:cc, XID 2c9, IRQ 36
>> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
>> Aug 7 23:19:12 tux kernel: RTL8211E Gigabit Ethernet r8169-400:00: attached PHY driver [RTL8211E Gigabit Ethernet] (mii_bus:phy_addr=r8169-400:00, irq=IGNORE)
>> Aug 7 23:19:13 tux kernel: r8169 0000:04:00.0 eth0: No native access to PCI extended config space, falling back to CSI
>>
>> and using fq_codel, of course.
>>
>> This cpuidle hiccup used to be completely gone without xmit_more and this was
>> the first (and so far only) time since merging it (regardless of load).
>> Also, while I'm using BMQ as CPU scheduler, that hasn't made a difference for
>> this particular problem in the past (with MuQSS/PDS) either; way back when I had
>> Eric's previous attempt(s) it also hiccupped with CFS.
>>
>> Revert or wait for more reports when -next is merged in 5.4?
>
> Another question/data point: I've had the whole basket of offloads activated:
>
> ethtool --offload eth0 rx on tx on gro on gso on sg on tso on
>
> and this caused zero problems without the xmit_more patch. However I just saw
> that net-next has a patch where TSO is disabled due to a known HW defect in
> RTL8168evl, which is of course what I have. Could this be the reason for the
> stall/hiccup when xmit_more has its fingers in the pie? I kind of know what
> xmit_more does, just not how it could interact with a possibly broken TSO that
> nevertheless seems to work fine otherwise..
>
I was about to ask exactly that, whether you have TSO enabled. I don't know what
can trigger the HW issue, it was just confirmed by Realtek that this chip version
has a problem with TSO. So the logical conclusion is: test w/o TSO, ideally the
linux-next version.
> thanks
> Holger
>
Heiner
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-08 18:17 ` Heiner Kallweit
@ 2019-08-08 19:52 ` Holger Hoffstätte
2019-08-08 20:08 ` Heiner Kallweit
0 siblings, 1 reply; 13+ messages in thread
From: Holger Hoffstätte @ 2019-08-08 19:52 UTC (permalink / raw)
To: Heiner Kallweit, Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
On 8/8/19 8:17 PM, Heiner Kallweit wrote:
> On 08.08.2019 17:53, Holger Hoffstätte wrote:
>> On 8/8/19 4:37 PM, Holger Hoffstätte wrote:
>>>
>>> Hello Heiner -
>>>
>>> On 7/28/19 11:25 AM, Heiner Kallweit wrote:
>>>> There was a previous attempt to use xmit_more, but the change had to be
>>>> reverted because under load sometimes a transmit timeout occurred [0].
>>>> Maybe this was caused by a missing memory barrier, the new attempt
>>>> keeps the memory barrier before the call to netif_stop_queue like it
>>>> is used by the driver as of today. The new attempt also changes the
>>>> order of some calls as suggested by Eric.
>>>>
>>>> [0] https://lkml.org/lkml/2019/2/10/39
>>>>
>>>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>>>
>>> I decided to take one for the team and merged this into my 5.2.x tree (just
>>> fixing up the path) and it has been working fine for the last 2 weeks in two
>>> machines..until today, when for the first time in forever some random NFS traffic
>>> made this old friend come out from under the couch:
>>>
>>> [Aug 8 14:13] ------------[ cut here ]------------
>>> [ +0.000006] NETDEV WATCHDOG: eth0 (r8169): transmit queue 0 timed out
>>> [ +0.000021] WARNING: CPU: 3 PID: 0 at net/sched/sch_generic.c:442 dev_watchdog+0x21f/0x230
>>> [ +0.000001] Modules linked in: lz4 lz4_compress lz4_decompress nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel btrfs xor zstd_compress raid6_pq zstd_decompress bfq jitterentropy_rng nct6775 hwmon_vid coretemp hwmon x86_pkg_temp_thermal aesni_intel aes_x86_64 i915 glue_helper crypto_simd cryptd i2c_i801 intel_gtt i2c_algo_bit iosf_mbi drm_kms_helper syscopyarea usbhid sysfillrect r8169 sysimgblt fb_sys_fops realtek drm libphy drm_panel_orientation_quirks i2c_core video backlight mq_deadline
>>> [ +0.000026] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.2.7 #1
>>> [ +0.000001] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
>>> [ +0.000004] RIP: 0010:dev_watchdog+0x21f/0x230
>>> [ +0.000002] Code: 3b 00 75 ea eb ad 4c 89 ef c6 05 1c 45 bd 00 01 e8 66 35 fc ff 44 89 e1 4c 89 ee 48 c7 c7 e8 5e fc 81 48 89 c2 e8 90 df 92 ff <0f> 0b eb 8e 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 66 66 66 66 90
>>> [ +0.000002] RSP: 0018:ffffc90000118e68 EFLAGS: 00010286
>>> [ +0.000002] RAX: 0000000000000000 RBX: ffff8887f7837600 RCX: 0000000000000303
>>> [ +0.000001] RDX: 0000000000000001 RSI: 0000000000000092 RDI: ffffffff827a488c
>>> [ +0.000001] RBP: ffff8887f9fbc440 R08: 0000000000000303 R09: 0000000000000003
>>> [ +0.000001] R10: 000000000001004c R11: 0000000000000001 R12: 0000000000000000
>>> [ +0.000009] R13: ffff8887f9fbc000 R14: ffffffff8173aa20 R15: dead000000000200
>>> [ +0.000001] FS: 0000000000000000(0000) GS:ffff8887ff580000(0000) knlGS:0000000000000000
>>> [ +0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [ +0.000001] CR2: 00007f8d1c04d000 CR3: 0000000002209001 CR4: 00000000000606e0
>>> [ +0.000000] Call Trace:
>>> [ +0.000002] <IRQ>
>>> [ +0.000005] call_timer_fn+0x2b/0x120
>>> [ +0.000002] expire_timers+0xa4/0x100
>>> [ +0.000001] run_timer_softirq+0x8c/0x170
>>> [ +0.000002] ? __hrtimer_run_queues+0x13a/0x290
>>> [ +0.000003] ? sched_clock_cpu+0xe/0x130
>>> [ +0.000003] __do_softirq+0xeb/0x2de
>>> [ +0.000003] irq_exit+0x9d/0xe0
>>> [ +0.000002] smp_apic_timer_interrupt+0x60/0x110
>>> [ +0.000003] apic_timer_interrupt+0xf/0x20
>>> [ +0.000001] </IRQ>
>>> [ +0.000003] RIP: 0010:cpuidle_enter_state+0xad/0x930
>>> [ +0.000001] Code: c5 66 66 66 66 90 31 ff e8 90 99 9e ff 80 7c 24 0b 00 74 12 9c 58 f6 c4 02 0f 85 39 08 00 00 31 ff e8 e7 26 a2 ff fb 45 85 e4 <0f> 88 34 02 00 00 49 63 cc 4c 2b 2c 24 48 8d 04 49 48 c1 e0 05 8b
>>> [ +0.000000] RSP: 0018:ffffc9000008be50 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
>>> [ +0.000001] RAX: ffff8887ff5a9180 RBX: ffffffff822b6c40 RCX: 000000000000001f
>>> [ +0.000001] RDX: 0000000000000000 RSI: 0000000033087154 RDI: 0000000000000000
>>> [ +0.000001] RBP: ffff8887ff5b1310 R08: 000030d021fae397 R09: ffff8887ff59c8c0
>>> [ +0.000000] R10: ffff8887ff59c8c0 R11: 0000000000000006 R12: 0000000000000004
>>> [ +0.000001] R13: 000030d021fae397 R14: 0000000000000004 R15: ffff8887fc281600
>>> [ +0.000001] cpuidle_enter+0x29/0x40
>>> [ +0.000002] do_idle+0x1e5/0x280
>>> [ +0.000001] cpu_startup_entry+0x19/0x20
>>> [ +0.000002] start_secondary+0x186/0x1c0
>>> [ +0.000001] secondary_startup_64+0xa4/0xb0
>>> [ +0.000001] ---[ end trace 99493c768580f4fd ]---
>>>
>>> The device is:
>>>
>>> Aug 7 23:19:09 tux kernel: libphy: r8169: probed
>>> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: RTL8168evl/8111evl, c8:60:00:68:33:cc, XID 2c9, IRQ 36
>>> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
>>> Aug 7 23:19:12 tux kernel: RTL8211E Gigabit Ethernet r8169-400:00: attached PHY driver [RTL8211E Gigabit Ethernet] (mii_bus:phy_addr=r8169-400:00, irq=IGNORE)
>>> Aug 7 23:19:13 tux kernel: r8169 0000:04:00.0 eth0: No native access to PCI extended config space, falling back to CSI
>>>
>>> and using fq_codel, of course.
>>>
>>> This cpuidle hiccup used to be completely gone without xmit_more and this was
>>> the first (and so far only) time since merging it (regardless of load).
>>> Also, while I'm using BMQ as CPU scheduler, that hasn't made a difference for
>>> this particular problem in the past (with MuQSS/PDS) either; way back when I had
>>> Eric's previous attempt(s) it also hiccupped with CFS.
>>>
>>> Revert or wait for more reports when -next is merged in 5.4?
>>
>> Another question/data point: I've had the whole basket of offloads activated:
>>
>> ethtool --offload eth0 rx on tx on gro on gso on sg on tso on
>>
>> and this caused zero problems without the xmit_more patch. However I just saw
>> that net-next has a patch where TSO is disabled due to a known HW defect in
>> RTL8168evl, which is of course what I have. Could this be the reason for the
>> stall/hiccup when xmit_more has its fingers in the pie? I kind of know what
>> xmit_more does, just not how it could interact with a possibly broken TSO that
>> nevertheless seems to work fine otherwise..
>>
>
> I was about to ask exactly that, whether you have TSO enabled. I don't know what
> can trigger the HW issue, it was just confirmed by Realtek that this chip version
> has a problem with TSO. So the logical conclusion is: test w/o TSO, ideally the
> linux-next version.
So disabling TSO alone didn't work - it leads to reduced throughout (~70 MB/s in iperf).
Instead I decided to backport 93681cd7d94f ("r8169: enable HW csum and TSO"), which
wasn't easy due to cleanups/renamings of dependencies, but I managed to backport
it and .. got the same problem of reduced throughout. wat?!
After lots of trial & error I started disabling all offloads and finally found
that sg (Scatter-Gather) enabled alone - without TSO - will lead to the throughput
drop. So the culprit seems 93681cd7d94f, which disabled TSO on my NIC, but left
sg on by default. This weas repeatable - switch on sg, throughput drop; turn it
off - smooth sailing, now with reduced buffers.
I modified the relevant bits to disable tso & sg like this:
/* RTL8168e-vl has a HW issue with TSO */
if (tp->mac_version == RTL_GIGA_MAC_VER_34) {
+ dev->vlan_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
+ dev->hw_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
+ dev->features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
}
This seems to work since it restores performance without sg/tso by default
and without any additional offloads, yet with xmit_more in the mix.
We'll see whether that is stable over the next few days, but I strongly
suspect it will be good and that the hiccups were due to xmit_more/TSO
interaction.
thanks,
Holger
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-08 19:52 ` Holger Hoffstätte
@ 2019-08-08 20:08 ` Heiner Kallweit
2019-08-09 8:04 ` Holger Hoffstätte
0 siblings, 1 reply; 13+ messages in thread
From: Heiner Kallweit @ 2019-08-08 20:08 UTC (permalink / raw)
To: Holger Hoffstätte, Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
On 08.08.2019 21:52, Holger Hoffstätte wrote:
> On 8/8/19 8:17 PM, Heiner Kallweit wrote:
>> On 08.08.2019 17:53, Holger Hoffstätte wrote:
>>> On 8/8/19 4:37 PM, Holger Hoffstätte wrote:
>>>>
>>>> Hello Heiner -
>>>>
>>>> On 7/28/19 11:25 AM, Heiner Kallweit wrote:
>>>>> There was a previous attempt to use xmit_more, but the change had to be
>>>>> reverted because under load sometimes a transmit timeout occurred [0].
>>>>> Maybe this was caused by a missing memory barrier, the new attempt
>>>>> keeps the memory barrier before the call to netif_stop_queue like it
>>>>> is used by the driver as of today. The new attempt also changes the
>>>>> order of some calls as suggested by Eric.
>>>>>
>>>>> [0] https://lkml.org/lkml/2019/2/10/39
>>>>>
>>>>> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
>>>>
>>>> I decided to take one for the team and merged this into my 5.2.x tree (just
>>>> fixing up the path) and it has been working fine for the last 2 weeks in two
>>>> machines..until today, when for the first time in forever some random NFS traffic
>>>> made this old friend come out from under the couch:
>>>>
>>>> [Aug 8 14:13] ------------[ cut here ]------------
>>>> [ +0.000006] NETDEV WATCHDOG: eth0 (r8169): transmit queue 0 timed out
>>>> [ +0.000021] WARNING: CPU: 3 PID: 0 at net/sched/sch_generic.c:442 dev_watchdog+0x21f/0x230
>>>> [ +0.000001] Modules linked in: lz4 lz4_compress lz4_decompress nfsd auth_rpcgss oid_registry lockd grace sunrpc sch_fq_codel btrfs xor zstd_compress raid6_pq zstd_decompress bfq jitterentropy_rng nct6775 hwmon_vid coretemp hwmon x86_pkg_temp_thermal aesni_intel aes_x86_64 i915 glue_helper crypto_simd cryptd i2c_i801 intel_gtt i2c_algo_bit iosf_mbi drm_kms_helper syscopyarea usbhid sysfillrect r8169 sysimgblt fb_sys_fops realtek drm libphy drm_panel_orientation_quirks i2c_core video backlight mq_deadline
>>>> [ +0.000026] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.2.7 #1
>>>> [ +0.000001] Hardware name: System manufacturer System Product Name/P8Z68-V LX, BIOS 4105 07/01/2013
>>>> [ +0.000004] RIP: 0010:dev_watchdog+0x21f/0x230
>>>> [ +0.000002] Code: 3b 00 75 ea eb ad 4c 89 ef c6 05 1c 45 bd 00 01 e8 66 35 fc ff 44 89 e1 4c 89 ee 48 c7 c7 e8 5e fc 81 48 89 c2 e8 90 df 92 ff <0f> 0b eb 8e 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 66 66 66 66 90
>>>> [ +0.000002] RSP: 0018:ffffc90000118e68 EFLAGS: 00010286
>>>> [ +0.000002] RAX: 0000000000000000 RBX: ffff8887f7837600 RCX: 0000000000000303
>>>> [ +0.000001] RDX: 0000000000000001 RSI: 0000000000000092 RDI: ffffffff827a488c
>>>> [ +0.000001] RBP: ffff8887f9fbc440 R08: 0000000000000303 R09: 0000000000000003
>>>> [ +0.000001] R10: 000000000001004c R11: 0000000000000001 R12: 0000000000000000
>>>> [ +0.000009] R13: ffff8887f9fbc000 R14: ffffffff8173aa20 R15: dead000000000200
>>>> [ +0.000001] FS: 0000000000000000(0000) GS:ffff8887ff580000(0000) knlGS:0000000000000000
>>>> [ +0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>> [ +0.000001] CR2: 00007f8d1c04d000 CR3: 0000000002209001 CR4: 00000000000606e0
>>>> [ +0.000000] Call Trace:
>>>> [ +0.000002] <IRQ>
>>>> [ +0.000005] call_timer_fn+0x2b/0x120
>>>> [ +0.000002] expire_timers+0xa4/0x100
>>>> [ +0.000001] run_timer_softirq+0x8c/0x170
>>>> [ +0.000002] ? __hrtimer_run_queues+0x13a/0x290
>>>> [ +0.000003] ? sched_clock_cpu+0xe/0x130
>>>> [ +0.000003] __do_softirq+0xeb/0x2de
>>>> [ +0.000003] irq_exit+0x9d/0xe0
>>>> [ +0.000002] smp_apic_timer_interrupt+0x60/0x110
>>>> [ +0.000003] apic_timer_interrupt+0xf/0x20
>>>> [ +0.000001] </IRQ>
>>>> [ +0.000003] RIP: 0010:cpuidle_enter_state+0xad/0x930
>>>> [ +0.000001] Code: c5 66 66 66 66 90 31 ff e8 90 99 9e ff 80 7c 24 0b 00 74 12 9c 58 f6 c4 02 0f 85 39 08 00 00 31 ff e8 e7 26 a2 ff fb 45 85 e4 <0f> 88 34 02 00 00 49 63 cc 4c 2b 2c 24 48 8d 04 49 48 c1 e0 05 8b
>>>> [ +0.000000] RSP: 0018:ffffc9000008be50 EFLAGS: 00000202 ORIG_RAX: ffffffffffffff13
>>>> [ +0.000001] RAX: ffff8887ff5a9180 RBX: ffffffff822b6c40 RCX: 000000000000001f
>>>> [ +0.000001] RDX: 0000000000000000 RSI: 0000000033087154 RDI: 0000000000000000
>>>> [ +0.000001] RBP: ffff8887ff5b1310 R08: 000030d021fae397 R09: ffff8887ff59c8c0
>>>> [ +0.000000] R10: ffff8887ff59c8c0 R11: 0000000000000006 R12: 0000000000000004
>>>> [ +0.000001] R13: 000030d021fae397 R14: 0000000000000004 R15: ffff8887fc281600
>>>> [ +0.000001] cpuidle_enter+0x29/0x40
>>>> [ +0.000002] do_idle+0x1e5/0x280
>>>> [ +0.000001] cpu_startup_entry+0x19/0x20
>>>> [ +0.000002] start_secondary+0x186/0x1c0
>>>> [ +0.000001] secondary_startup_64+0xa4/0xb0
>>>> [ +0.000001] ---[ end trace 99493c768580f4fd ]---
>>>>
>>>> The device is:
>>>>
>>>> Aug 7 23:19:09 tux kernel: libphy: r8169: probed
>>>> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: RTL8168evl/8111evl, c8:60:00:68:33:cc, XID 2c9, IRQ 36
>>>> Aug 7 23:19:09 tux kernel: r8169 0000:04:00.0 eth0: jumbo features [frames: 9200 bytes, tx checksumming: ko]
>>>> Aug 7 23:19:12 tux kernel: RTL8211E Gigabit Ethernet r8169-400:00: attached PHY driver [RTL8211E Gigabit Ethernet] (mii_bus:phy_addr=r8169-400:00, irq=IGNORE)
>>>> Aug 7 23:19:13 tux kernel: r8169 0000:04:00.0 eth0: No native access to PCI extended config space, falling back to CSI
>>>>
>>>> and using fq_codel, of course.
>>>>
>>>> This cpuidle hiccup used to be completely gone without xmit_more and this was
>>>> the first (and so far only) time since merging it (regardless of load).
>>>> Also, while I'm using BMQ as CPU scheduler, that hasn't made a difference for
>>>> this particular problem in the past (with MuQSS/PDS) either; way back when I had
>>>> Eric's previous attempt(s) it also hiccupped with CFS.
>>>>
>>>> Revert or wait for more reports when -next is merged in 5.4?
>>>
>>> Another question/data point: I've had the whole basket of offloads activated:
>>>
>>> ethtool --offload eth0 rx on tx on gro on gso on sg on tso on
>>>
>>> and this caused zero problems without the xmit_more patch. However I just saw
>>> that net-next has a patch where TSO is disabled due to a known HW defect in
>>> RTL8168evl, which is of course what I have. Could this be the reason for the
>>> stall/hiccup when xmit_more has its fingers in the pie? I kind of know what
>>> xmit_more does, just not how it could interact with a possibly broken TSO that
>>> nevertheless seems to work fine otherwise..
>>>
>>
>> I was about to ask exactly that, whether you have TSO enabled. I don't know what
>> can trigger the HW issue, it was just confirmed by Realtek that this chip version
>> has a problem with TSO. So the logical conclusion is: test w/o TSO, ideally the
>> linux-next version.
>
> So disabling TSO alone didn't work - it leads to reduced throughout (~70 MB/s in iperf).
> Instead I decided to backport 93681cd7d94f ("r8169: enable HW csum and TSO"), which
> wasn't easy due to cleanups/renamings of dependencies, but I managed to backport
> it and .. got the same problem of reduced throughout. wat?!
>
> After lots of trial & error I started disabling all offloads and finally found
> that sg (Scatter-Gather) enabled alone - without TSO - will lead to the throughput
> drop. So the culprit seems 93681cd7d94f, which disabled TSO on my NIC, but left
> sg on by default. This weas repeatable - switch on sg, throughput drop; turn it
> off - smooth sailing, now with reduced buffers.
>
> I modified the relevant bits to disable tso & sg like this:
>
> /* RTL8168e-vl has a HW issue with TSO */
> if (tp->mac_version == RTL_GIGA_MAC_VER_34) {
> + dev->vlan_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
> + dev->hw_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
> + dev->features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
> }
>
> This seems to work since it restores performance without sg/tso by default
> and without any additional offloads, yet with xmit_more in the mix.
> We'll see whether that is stable over the next few days, but I strongly
> suspect it will be good and that the hiccups were due to xmit_more/TSO
> interaction.
>
Thanks a lot for the analysis and testing. Then I'll submit the disabling
of SG on RTL8168evl (on your behalf), independent of whether it fixes
the timeout issue.
> thanks,
> Holger
>
Heiner
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-08 20:08 ` Heiner Kallweit
@ 2019-08-09 8:04 ` Holger Hoffstätte
2019-08-09 8:25 ` Eric Dumazet
0 siblings, 1 reply; 13+ messages in thread
From: Holger Hoffstätte @ 2019-08-09 8:04 UTC (permalink / raw)
To: Heiner Kallweit, Realtek linux nic maintainers, David Miller
Cc: netdev, Sander Eikelenboom, Eric Dumazet
On 8/8/19 10:08 PM, Heiner Kallweit wrote:
(..snip..)
>>>
>>> I was about to ask exactly that, whether you have TSO enabled. I don't know what
>>> can trigger the HW issue, it was just confirmed by Realtek that this chip version
>>> has a problem with TSO. So the logical conclusion is: test w/o TSO, ideally the
>>> linux-next version.
>>
>> So disabling TSO alone didn't work - it leads to reduced throughout (~70 MB/s in iperf).
>> Instead I decided to backport 93681cd7d94f ("r8169: enable HW csum and TSO"), which
>> wasn't easy due to cleanups/renamings of dependencies, but I managed to backport
>> it and .. got the same problem of reduced throughout. wat?!
>>
>> After lots of trial & error I started disabling all offloads and finally found
>> that sg (Scatter-Gather) enabled alone - without TSO - will lead to the throughput
>> drop. So the culprit seems 93681cd7d94f, which disabled TSO on my NIC, but left
>> sg on by default. This weas repeatable - switch on sg, throughput drop; turn it
>> off - smooth sailing, now with reduced buffers.
>>
>> I modified the relevant bits to disable tso & sg like this:
>>
>> /* RTL8168e-vl has a HW issue with TSO */
>> if (tp->mac_version == RTL_GIGA_MAC_VER_34) {
>> + dev->vlan_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
>> + dev->hw_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
>> + dev->features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
>> }
>>
>> This seems to work since it restores performance without sg/tso by default
>> and without any additional offloads, yet with xmit_more in the mix.
>> We'll see whether that is stable over the next few days, but I strongly
>> suspect it will be good and that the hiccups were due to xmit_more/TSO
>> interaction.
So that didn't take long - got another timeout this morning during some
random light usage, despite sg/tso being disabled this time.
Again the only common element is the xmit_more patch. :(
Not sure whether you want to revert this right away or wait for 5.4-rc1
feedback. Maybe this too is chipset-specific?
> Thanks a lot for the analysis and testing. Then I'll submit the disabling
> of SG on RTL8168evl (on your behalf), independent of whether it fixes
> the timeout issue.
Got it, thanks!
Holger
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-09 8:04 ` Holger Hoffstätte
@ 2019-08-09 8:25 ` Eric Dumazet
2019-08-09 8:52 ` Holger Hoffstätte
0 siblings, 1 reply; 13+ messages in thread
From: Eric Dumazet @ 2019-08-09 8:25 UTC (permalink / raw)
To: Holger Hoffstätte
Cc: Heiner Kallweit, Realtek linux nic maintainers, David Miller,
netdev, Sander Eikelenboom
On Fri, Aug 9, 2019 at 10:04 AM Holger Hoffstätte
<holger@applied-asynchrony.com> wrote:
>
> On 8/8/19 10:08 PM, Heiner Kallweit wrote:
> (..snip..)
> >>>
> >>> I was about to ask exactly that, whether you have TSO enabled. I don't know what
> >>> can trigger the HW issue, it was just confirmed by Realtek that this chip version
> >>> has a problem with TSO. So the logical conclusion is: test w/o TSO, ideally the
> >>> linux-next version.
> >>
> >> So disabling TSO alone didn't work - it leads to reduced throughout (~70 MB/s in iperf).
> >> Instead I decided to backport 93681cd7d94f ("r8169: enable HW csum and TSO"), which
> >> wasn't easy due to cleanups/renamings of dependencies, but I managed to backport
> >> it and .. got the same problem of reduced throughout. wat?!
> >>
> >> After lots of trial & error I started disabling all offloads and finally found
> >> that sg (Scatter-Gather) enabled alone - without TSO - will lead to the throughput
> >> drop. So the culprit seems 93681cd7d94f, which disabled TSO on my NIC, but left
> >> sg on by default. This weas repeatable - switch on sg, throughput drop; turn it
> >> off - smooth sailing, now with reduced buffers.
> >>
> >> I modified the relevant bits to disable tso & sg like this:
> >>
> >> /* RTL8168e-vl has a HW issue with TSO */
> >> if (tp->mac_version == RTL_GIGA_MAC_VER_34) {
> >> + dev->vlan_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
> >> + dev->hw_features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
> >> + dev->features &= ~(NETIF_F_ALL_TSO|NETIF_F_SG);
> >> }
> >>
> >> This seems to work since it restores performance without sg/tso by default
> >> and without any additional offloads, yet with xmit_more in the mix.
> >> We'll see whether that is stable over the next few days, but I strongly
> >> suspect it will be good and that the hiccups were due to xmit_more/TSO
> >> interaction.
>
> So that didn't take long - got another timeout this morning during some
> random light usage, despite sg/tso being disabled this time.
> Again the only common element is the xmit_more patch. :(
> Not sure whether you want to revert this right away or wait for 5.4-rc1
> feedback. Maybe this too is chipset-specific?
>
> > Thanks a lot for the analysis and testing. Then I'll submit the disabling
> > of SG on RTL8168evl (on your behalf), independent of whether it fixes
> > the timeout issue.
>
> Got it, thanks!
>
> Holger
I would try this fix maybe ?
diff --git a/drivers/net/ethernet/realtek/r8169_main.c
b/drivers/net/ethernet/realtek/r8169_main.c
index b2a275d8504cf099cff738f2f7554efa9658fe32..e77628813daba493ad50dab9ac1e3703e38b560c
100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -5691,6 +5691,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
*/
smp_wmb();
netif_stop_queue(dev);
+ door_bell = true;
}
if (door_bell)
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-09 8:25 ` Eric Dumazet
@ 2019-08-09 8:52 ` Holger Hoffstätte
2019-08-09 20:28 ` Heiner Kallweit
2019-08-12 9:59 ` Holger Hoffstätte
0 siblings, 2 replies; 13+ messages in thread
From: Holger Hoffstätte @ 2019-08-09 8:52 UTC (permalink / raw)
To: Eric Dumazet
Cc: Heiner Kallweit, Realtek linux nic maintainers, David Miller,
netdev, Sander Eikelenboom
On 8/9/19 10:25 AM, Eric Dumazet wrote:
(snip)
>>
>> So that didn't take long - got another timeout this morning during some
>> random light usage, despite sg/tso being disabled this time.
>> Again the only common element is the xmit_more patch. :(
>> Not sure whether you want to revert this right away or wait for 5.4-rc1
>> feedback. Maybe this too is chipset-specific?
>>
>>> Thanks a lot for the analysis and testing. Then I'll submit the disabling
>>> of SG on RTL8168evl (on your behalf), independent of whether it fixes
>>> the timeout issue.
>>
>> Got it, thanks!
>>
>> Holger
>
> I would try this fix maybe ?
>
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c
> b/drivers/net/ethernet/realtek/r8169_main.c
> index b2a275d8504cf099cff738f2f7554efa9658fe32..e77628813daba493ad50dab9ac1e3703e38b560c
> 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -5691,6 +5691,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
> */
> smp_wmb();
> netif_stop_queue(dev);
> + door_bell = true;
> }
>
> if (door_bell)
>
Thanks Eric, I'll give that a try and see how it fares over the next few days.
It suspiciously looks like it could help..
-h
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-09 8:52 ` Holger Hoffstätte
@ 2019-08-09 20:28 ` Heiner Kallweit
2019-08-12 9:59 ` Holger Hoffstätte
1 sibling, 0 replies; 13+ messages in thread
From: Heiner Kallweit @ 2019-08-09 20:28 UTC (permalink / raw)
To: Holger Hoffstätte, Eric Dumazet
Cc: Realtek linux nic maintainers, David Miller, netdev, Sander Eikelenboom
On 09.08.2019 10:52, Holger Hoffstätte wrote:
> On 8/9/19 10:25 AM, Eric Dumazet wrote:
> (snip)
>>>
>>> So that didn't take long - got another timeout this morning during some
>>> random light usage, despite sg/tso being disabled this time.
>>> Again the only common element is the xmit_more patch. :(
>>> Not sure whether you want to revert this right away or wait for 5.4-rc1
>>> feedback. Maybe this too is chipset-specific?
>>>
>>>> Thanks a lot for the analysis and testing. Then I'll submit the disabling
>>>> of SG on RTL8168evl (on your behalf), independent of whether it fixes
>>>> the timeout issue.
>>>
>>> Got it, thanks!
>>>
>>> Holger
>>
>> I would try this fix maybe ?
>>
>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c
>> b/drivers/net/ethernet/realtek/r8169_main.c
>> index b2a275d8504cf099cff738f2f7554efa9658fe32..e77628813daba493ad50dab9ac1e3703e38b560c
>> 100644
>> --- a/drivers/net/ethernet/realtek/r8169_main.c
>> +++ b/drivers/net/ethernet/realtek/r8169_main.c
>> @@ -5691,6 +5691,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
>> */
>> smp_wmb();
>> netif_stop_queue(dev);
>> + door_bell = true;
>> }
>>
>> if (door_bell)
>>
>
> Thanks Eric, I'll give that a try and see how it fares over the next few days.
> It suspiciously looks like it could help..
>
> -h
>
Thanks for testing this. Looking forward to your feedback regarding the change.
Heiner
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-09 8:52 ` Holger Hoffstätte
2019-08-09 20:28 ` Heiner Kallweit
@ 2019-08-12 9:59 ` Holger Hoffstätte
2019-08-12 18:38 ` Heiner Kallweit
1 sibling, 1 reply; 13+ messages in thread
From: Holger Hoffstätte @ 2019-08-12 9:59 UTC (permalink / raw)
To: Eric Dumazet
Cc: Heiner Kallweit, Realtek linux nic maintainers, David Miller,
netdev, Sander Eikelenboom
On 8/9/19 10:52 AM, Holger Hoffstätte wrote:
> On 8/9/19 10:25 AM, Eric Dumazet wrote:
> (snip)
>>>
>>> So that didn't take long - got another timeout this morning during some
>>> random light usage, despite sg/tso being disabled this time.
>>> Again the only common element is the xmit_more patch. :(
>>> Not sure whether you want to revert this right away or wait for 5.4-rc1
>>> feedback. Maybe this too is chipset-specific?
>>>
>>>> Thanks a lot for the analysis and testing. Then I'll submit the disabling
>>>> of SG on RTL8168evl (on your behalf), independent of whether it fixes
>>>> the timeout issue.
>>>
>>> Got it, thanks!
>>>
>>> Holger
>>
>> I would try this fix maybe ?
>>
>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c
>> b/drivers/net/ethernet/realtek/r8169_main.c
>> index b2a275d8504cf099cff738f2f7554efa9658fe32..e77628813daba493ad50dab9ac1e3703e38b560c
>> 100644
>> --- a/drivers/net/ethernet/realtek/r8169_main.c
>> +++ b/drivers/net/ethernet/realtek/r8169_main.c
>> @@ -5691,6 +5691,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
>> */
>> smp_wmb();
>> netif_stop_queue(dev);
>> + door_bell = true;
>> }
>>
>> if (door_bell)
>>
>
> Thanks Eric, I'll give that a try and see how it fares over the next few days.
> It suspiciously looks like it could help..
Good news everyone!
After three days non-stop action between two machines and hundreds of GBs
pushed back and forth: not a single timeout or hiccup. Nice! \o/
Eric, please send this as a proper patch for -next. Feel free to add my
Tested-by.
cheers
Holger
^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [PATCH net-next] r8169: make use of xmit_more
2019-08-12 9:59 ` Holger Hoffstätte
@ 2019-08-12 18:38 ` Heiner Kallweit
0 siblings, 0 replies; 13+ messages in thread
From: Heiner Kallweit @ 2019-08-12 18:38 UTC (permalink / raw)
To: Holger Hoffstätte, Eric Dumazet
Cc: Realtek linux nic maintainers, David Miller, netdev, Sander Eikelenboom
On 12.08.2019 11:59, Holger Hoffstätte wrote:
> On 8/9/19 10:52 AM, Holger Hoffstätte wrote:
>> On 8/9/19 10:25 AM, Eric Dumazet wrote:
>> (snip)
>>>>
>>>> So that didn't take long - got another timeout this morning during some
>>>> random light usage, despite sg/tso being disabled this time.
>>>> Again the only common element is the xmit_more patch. :(
>>>> Not sure whether you want to revert this right away or wait for 5.4-rc1
>>>> feedback. Maybe this too is chipset-specific?
>>>>
>>>>> Thanks a lot for the analysis and testing. Then I'll submit the disabling
>>>>> of SG on RTL8168evl (on your behalf), independent of whether it fixes
>>>>> the timeout issue.
>>>>
>>>> Got it, thanks!
>>>>
>>>> Holger
>>>
>>> I would try this fix maybe ?
>>>
>>> diff --git a/drivers/net/ethernet/realtek/r8169_main.c
>>> b/drivers/net/ethernet/realtek/r8169_main.c
>>> index b2a275d8504cf099cff738f2f7554efa9658fe32..e77628813daba493ad50dab9ac1e3703e38b560c
>>> 100644
>>> --- a/drivers/net/ethernet/realtek/r8169_main.c
>>> +++ b/drivers/net/ethernet/realtek/r8169_main.c
>>> @@ -5691,6 +5691,7 @@ static netdev_tx_t rtl8169_start_xmit(struct sk_buff *skb,
>>> */
>>> smp_wmb();
>>> netif_stop_queue(dev);
>>> + door_bell = true;
>>> }
>>>
>>> if (door_bell)
>>>
>>
>> Thanks Eric, I'll give that a try and see how it fares over the next few days.
>> It suspiciously looks like it could help..
>
> Good news everyone!
>
> After three days non-stop action between two machines and hundreds of GBs
> pushed back and forth: not a single timeout or hiccup. Nice! \o/
> Eric, please send this as a proper patch for -next. Feel free to add my
> Tested-by.
>
Thanks for the feedback! I can submit the fix with Eric's "Suggested-by".
> cheers
> Holger
>
Heiner
^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2019-08-12 18:38 UTC | newest]
Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-07-28 9:25 [PATCH net-next] r8169: make use of xmit_more Heiner Kallweit
2019-07-29 18:05 ` David Miller
2019-08-08 14:37 ` Holger Hoffstätte
2019-08-08 15:53 ` Holger Hoffstätte
2019-08-08 18:17 ` Heiner Kallweit
2019-08-08 19:52 ` Holger Hoffstätte
2019-08-08 20:08 ` Heiner Kallweit
2019-08-09 8:04 ` Holger Hoffstätte
2019-08-09 8:25 ` Eric Dumazet
2019-08-09 8:52 ` Holger Hoffstätte
2019-08-09 20:28 ` Heiner Kallweit
2019-08-12 9:59 ` Holger Hoffstätte
2019-08-12 18:38 ` Heiner Kallweit
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