From: Eric Dumazet <eric.dumazet@gmail.com>
To: Netanel Belgazal <netanel@annapurnalabs.com>
Cc: linux-kernel@vger.kernel.org, davem@davemloft.net,
netdev@vger.kernel.org, dwmw@amazon.com, zorik@annapurnalabs.com,
alex@annapurnalabs.com, saeed@annapurnalabs.com, msw@amazon.com,
aliguori@amazon.com, nafea@annapurnalabs.com
Subject: Re: [PATCH V2 net 10/20] net/ena: remove redundant logic in napi callback for busy poll mode
Date: Sun, 04 Dec 2016 21:45:39 -0800 [thread overview]
Message-ID: <1480916739.18162.516.camel@edumazet-glaptop3.roam.corp.google.com> (raw)
In-Reply-To: <1480857578-5065-11-git-send-email-netanel@annapurnalabs.com>
On Sun, 2016-12-04 at 15:19 +0200, Netanel Belgazal wrote:
> sk_busy_loop can call the napi callback few million times a sec.
> For each call there is unmask interrupt.
> We want to reduce the number of unmasks.
>
> Add an atomic variable that will tell the napi handler if
> it was called from irq context or not.
> Unmask the interrupt only from irq context.
>
> A schenario where the driver left with missed unmask isn't feasible.
> when ena_intr_msix_io is called the driver have 2 options:
> 1)Before napi completes and call napi_complete_done
> 2)After calling napi_complete_done
>
> In the former case the napi will unmask the interrupt as needed.
> In the latter case napi_complete_done will remove napi from the schedule
> list so napi will be rescheduled (by ena_intr_msix_io) and interrupt
> will be unmasked as desire in the 2nd napi call.
>
> Signed-off-by: Netanel Belgazal <netanel@annapurnalabs.com>
> ---
This looks very complicated to me.
I guess you missed the recent patches that happened on net-next ?
2e713283751f494596655d9125c168aeb913f71d net/mlx4_en: use napi_complete_done() return value
364b6055738b4c752c30ccaaf25c624e69d76195 net: busy-poll: return busypolling status to drivers
21cb84c48ca0619181106f0f44f3802a989de024 net: busy-poll: remove need_resched() from sk_can_busy_loop()
217f6974368188fd8bd7804bf5a036aa5762c5e4 net: busy-poll: allow preemption in sk_busy_loop()
napi_complete_done() return code can be used by a driver,
no need to add yet another atomic operation in fast path.
Anyway, this looks wrong :
@@ -1186,6 +1201,7 @@ static irqreturn_t ena_intr_msix_io(int irq, void *data)
{
struct ena_napi *ena_napi = data;
+ atomic_set(&ena_napi->unmask_interrupt, 1);
napi_schedule(&ena_napi->napi);
You probably wanted :
if (napi_schedule_prep(n)) {
atomic_set(&ena_napi->unmask_interrupt, 1);
__napi_schedule(n);
}
Please rework this napi poll using core infrastructure.
busypoll logic should be centralized, not reimplemented in different ways in a driver.
Thanks.
next prev parent reply other threads:[~2016-12-05 5:58 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-04 13:19 [PATCH V2 net 00/20] Increase ENA driver version to 1.1.2 Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 01/20] net/ena: remove ntuple filter support from device feature list Netanel Belgazal
2016-12-05 4:08 ` Matt Wilson
2016-12-04 13:19 ` [PATCH V2 net 02/20] net/ena: fix error handling when probe fails Netanel Belgazal
2016-12-05 4:09 ` Matt Wilson
2016-12-05 18:23 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 03/20] net/ena: fix queues number calculation Netanel Belgazal
2016-12-05 4:11 ` Matt Wilson
2016-12-05 18:25 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 04/20] net/ena: fix ethtool RSS flow configuration Netanel Belgazal
2016-12-05 4:18 ` Matt Wilson
2016-12-05 18:26 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 05/20] net/ena: fix RSS default hash configuration Netanel Belgazal
2016-12-05 4:20 ` Matt Wilson
2016-12-05 18:32 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 06/20] net/ena: fix NULL dereference when removing the driver after device reset faild Netanel Belgazal
2016-12-05 4:29 ` Matt Wilson
2016-12-05 18:30 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 07/20] net/ena: refactor ena_get_stats64 to be atomic context safe Netanel Belgazal
2016-12-05 4:24 ` Matt Wilson
2016-12-05 18:29 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 08/20] net/ena: add hardware hints capability to the driver Netanel Belgazal
2016-12-05 4:31 ` Matt Wilson
2016-12-05 18:31 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 09/20] net/ena: fix potential access to freed memory during device reset Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 10/20] net/ena: remove redundant logic in napi callback for busy poll mode Netanel Belgazal
2016-12-05 5:45 ` Eric Dumazet [this message]
2016-12-05 18:29 ` Netanel Belgazal
2016-12-05 18:51 ` Eric Dumazet
2016-12-04 13:19 ` [PATCH V2 net 11/20] net/ena: use READ_ONCE to access completion descriptors Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 12/20] net/ena: reduce the severity of ena printouts Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 13/20] net/ena: change driver's default timeouts Netanel Belgazal
2016-12-05 4:35 ` Matt Wilson
2016-12-05 18:28 ` Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 14/20] net/ena: change condition for host attribute configuration Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 15/20] net/ena: change sizeof() argument to be the type pointer Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 16/20] net/ena: use napi_schedule_irqoff when possible Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 17/20] net/ena: add IPv6 extended protocols to ena_admin_flow_hash_proto Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 18/20] net/ena: remove affinity hint from the driver Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 19/20] net/ena: restructure skb allocation Netanel Belgazal
2016-12-04 13:19 ` [PATCH V2 net 20/20] net/ena: increase driver version to 1.1.2 Netanel Belgazal
2016-12-05 2:37 ` [PATCH V2 net 00/20] Increase ENA " David Miller
2016-12-05 3:30 ` Matt Wilson
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