* [PATCH v3] storvsc: use small sg_tablesize on x86
@ 2016-06-09 16:25 Olaf Hering
2016-06-09 17:25 ` James Bottomley
0 siblings, 1 reply; 4+ messages in thread
From: Olaf Hering @ 2016-06-09 16:25 UTC (permalink / raw)
To: K. Y. Srinivasan, Haiyang Zhang, James E.J. Bottomley,
Martin K. Petersen
Cc: devel, linux-kernel, linux-scsi, Olaf Hering
Reducing the sg_tablesize allows booting of 32bit kernels in VMs, after
commit be0cf6ca301c61458dc4aa1a37acf4f58d2ed3d6 ("scsi: storvsc: Set the
tablesize based on the information given by the host")
[ 5.567138] hv_storvsc vmbus_1: adjusting sg_tablesize 0x800 -> 0x20
Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
As requested, use CONFIG_<bitsize>. For some reason IS_ENABLED(64_BIT)
does not work.
drivers/scsi/storvsc_drv.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 3ddcabb..ae42324 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1673,11 +1673,15 @@ static int storvsc_probe(struct hv_device *device,
/* max cmd length */
host->max_cmd_len = STORVSC_MAX_CMD_LEN;
+#ifdef CONFIG_64BIT
/*
* set the table size based on the info we got
* from the host.
*/
host->sg_tablesize = (stor_device->max_transfer_bytes >> PAGE_SHIFT);
+#else
+ host->sg_tablesize = MAX_MULTIPAGE_BUFFER_COUNT;
+#endif
/* Register the HBA and start the scsi bus scan */
ret = scsi_add_host(host, &device->device);
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3] storvsc: use small sg_tablesize on x86
2016-06-09 16:25 [PATCH v3] storvsc: use small sg_tablesize on x86 Olaf Hering
@ 2016-06-09 17:25 ` James Bottomley
2016-06-09 22:01 ` Olaf Hering
0 siblings, 1 reply; 4+ messages in thread
From: James Bottomley @ 2016-06-09 17:25 UTC (permalink / raw)
To: Olaf Hering, K. Y. Srinivasan, Haiyang Zhang, Martin K. Petersen
Cc: devel, linux-kernel, linux-scsi
On Thu, 2016-06-09 at 18:25 +0200, Olaf Hering wrote:
> Reducing the sg_tablesize allows booting of 32bit kernels in VMs,
> after
> commit be0cf6ca301c61458dc4aa1a37acf4f58d2ed3d6 ("scsi: storvsc: Set
> the
> tablesize based on the information given by the host")
>
> [ 5.567138] hv_storvsc vmbus_1: adjusting sg_tablesize 0x800 ->
> 0x20
Are you really sure 32 is the correct size? That caps transfers at 128
k. Even in the dim, dark, pre-64bit (at least on x86) days, our static
limit for sg tablesize was 128 (0.5M).
I know 32 it what it had before, but the reason for the commit you
quote was to improve performance ...
James
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] storvsc: use small sg_tablesize on x86
2016-06-09 17:25 ` James Bottomley
@ 2016-06-09 22:01 ` Olaf Hering
2016-06-15 2:07 ` Martin K. Petersen
0 siblings, 1 reply; 4+ messages in thread
From: Olaf Hering @ 2016-06-09 22:01 UTC (permalink / raw)
To: James Bottomley
Cc: K. Y. Srinivasan, Haiyang Zhang, Martin K. Petersen, devel,
linux-kernel, linux-scsi
On Thu, Jun 09, James Bottomley wrote:
> On Thu, 2016-06-09 at 18:25 +0200, Olaf Hering wrote:
> > Reducing the sg_tablesize allows booting of 32bit kernels in VMs,
> > after
> > commit be0cf6ca301c61458dc4aa1a37acf4f58d2ed3d6 ("scsi: storvsc: Set
> > the
> > tablesize based on the information given by the host")
> >
> > [ 5.567138] hv_storvsc vmbus_1: adjusting sg_tablesize 0x800 ->
> > 0x20
>
> Are you really sure 32 is the correct size?
Its a size that works, while the current state does not work at all.
> I know 32 it what it had before, but the reason for the commit you
> quote was to improve performance ...
The commit above broke 32bit. Whoever wants to improve performance on
this dead horse can submit another patch.
Olaf
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] storvsc: use small sg_tablesize on x86
2016-06-09 22:01 ` Olaf Hering
@ 2016-06-15 2:07 ` Martin K. Petersen
0 siblings, 0 replies; 4+ messages in thread
From: Martin K. Petersen @ 2016-06-15 2:07 UTC (permalink / raw)
To: Olaf Hering
Cc: James Bottomley, K. Y. Srinivasan, Haiyang Zhang,
Martin K. Petersen, devel, linux-kernel, linux-scsi
>>>>> "Olaf" == Olaf Hering <olaf@aepfle.de> writes:
Olaf> On Thu, Jun 09, James Bottomley wrote:
>> On Thu, 2016-06-09 at 18:25 +0200, Olaf Hering wrote:
>> > Reducing the sg_tablesize allows booting of 32bit kernels in VMs, >
>> after > commit be0cf6ca301c61458dc4aa1a37acf4f58d2ed3d6 ("scsi:
>> storvsc: Set > the > tablesize based on the information given by the
>> host")
>> >
>> > [ 5.567138] hv_storvsc vmbus_1: adjusting sg_tablesize 0x800 -> >
>> 0x20
>>
>> Are you really sure 32 is the correct size?
Olaf> Its a size that works, while the current state does not work at
Olaf> all.
>> I know 32 it what it had before, but the reason for the commit you
>> quote was to improve performance ...
Olaf> The commit above broke 32bit. Whoever wants to improve performance
Olaf> on this dead horse can submit another patch.
K.Y.?
--
Martin K. Petersen Oracle Linux Engineering
^ permalink raw reply [flat|nested] 4+ messages in thread
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2016-06-09 16:25 [PATCH v3] storvsc: use small sg_tablesize on x86 Olaf Hering
2016-06-09 17:25 ` James Bottomley
2016-06-09 22:01 ` Olaf Hering
2016-06-15 2:07 ` Martin K. Petersen
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