On Tue, Apr 6, 2021 at 2:33 PM Yufen Yu <yuyufen@xxxxxxxxxx> wrote:
>
> gentle ping.
> Any suggestion are welcome.
>
> Thanks,
> Yufen
>
>
>
> On 2021/3/25 16:42, Yufen Yu wrote:
> > Before commit 132147d7f620 ("scsi: megaraid_sas: Add support for
> > High IOPS queues"), all interrupt of megaraid_sas is managed when
> > smp_affinity_enable for misx_enable. The mapping between vectors and
> > cpus for a 128 vectors likely:
> > vector0 maps to cpu0
> > vector1 maps to cpu1
> > ...
> > If cpu0 is offline, vector0 cannot handle any io.
> >
> > For now, we have not pointed msix index in megasas_build_ld_nonrw_fusion().
> > The default value of index is '0'. So, cmd like TEST_UNIT_READY will hung
> > forever after cpu0 offline. We can simplely reproduce by:
> >
> > echo 0 > /sys/devices/system/cpu/cpu0/online
> > sg_turs /dev/sda # hung
> >
> > After commit 132147d7f620, low_latency_index_start is set as 1 (not sure
> > for all scenario), then vector 0 is not managed. Thus, io issue to vector0
> > can be handled by other cpus after cpu0 offline.
> >
> > Nevertheless, we may also conside to set msix index rather than default 0
> > in megasas_build_ld_nonrw_fusion().
This patch does not seem critical. We don't want to change the
behavior at this point
as this driver supports a lot of old controllers and we cannot risk
breaking any of
the supported controllers. Anyways MSI-x 0 is used for non- IO frames only so
no performance gain too with this change.
Hence, NACK for this patch.
> >
> > Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
> > ---
> > drivers/scsi/megaraid/megaraid_sas_fusion.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/scsi/megaraid/megaraid_sas_fusion.c b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > index 38fc9467c625..ddc6176f12c4 100644
> > --- a/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > +++ b/drivers/scsi/megaraid/megaraid_sas_fusion.c
> > @@ -3021,6 +3021,8 @@ static void megasas_build_ld_nonrw_fusion(struct megasas_instance *instance,
> > io_request->Function = MPI2_FUNCTION_SCSI_IO_REQUEST;
> > io_request->DevHandle = devHandle;
> > }
> > +
> > + megasas_get_msix_index(instance, scmd, cmd, 1);
> > }
> >
> > /**
> >
Attachment:
smime.p7s
Description: S/MIME Cryptographic Signature
