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From: Kashyap Desai <kashyap.desai@broadcom.com>
To: John Garry <john.garry@huawei.com>,
	axboe@kernel.dk, jejb@linux.ibm.com, martin.petersen@oracle.com,
	don.brace@microsemi.com, Sumit Saxena <sumit.saxena@broadcom.com>,
	ming.lei@redhat.com, bvanassche@acm.org, hare@suse.com,
	hch@lst.de,
	Shivasharan Srikanteshwara 
	<shivasharan.srikanteshwara@broadcom.com>
Cc: linux-block@vger.kernel.org, linux-scsi@vger.kernel.org,
	esc.storagedev@microsemi.com, chenxiang66@hisilicon.com,
	"PDL,MEGARAIDLINUX" <megaraidlinux.pdl@broadcom.com>
Subject: RE: [PATCH RFC v7 10/12] megaraid_sas: switch fusion adapters to MQ
Date: Fri, 10 Jul 2020 00:31:44 +0530	[thread overview]
Message-ID: <b49c33ebda36b8f116a51bc5c430eb9d@mail.gmail.com> (raw)
In-Reply-To: <61299951-97dc-b2be-c66c-024dfbd3a1cb@huawei.com>

> >> If you want to share an updated megaraid sas driver patch based on
> >> that, then that's fine. I can incorporate that change in the patch
> >> where we add host_tagset to the scsi host template.
> > If you share git repo link of next submission, I can send you
> > megaraid_sas driver patch which you can include in series.
>
> So this is my work-en-progress branch:
>
> https://github.com/hisilicon/kernel-dev/commits/private-topic-blk-mq-
> shared-tags-rfc-v8

I tested this repo + megaraid_sas shared hosttag driver. This repo (5.8-rc)
has CPU hotplug patch.
" bf0beec0607d blk-mq: drain I/O when all CPUs in a hctx are offline"

Looking at description of above patch and changes, it looks like
megaraid_sas driver can still work without shared host tag for this feature.

I observe CPU hotplug works irrespective of shared host tag in megaraid_sas
on 5.8-rc.

Without shared host tag, megaraid driver will expose single hctx and all the
CPU will be mapped to hctx0.
Any CPU offline event will have " blk_mq_hctx_notify_offline" callback in
blk-mq module. If we do not have this callback/patch, we will see IO
timeout.
blk_mq_hctx_notify_offline callback will make sure all the outstanding on
hctx0 is cleared and only after it is cleared, CPU will go offline.

megaraid_sas driver has  internal reply_queue mapping which helps to get IO
completion on same cpu.  Driver get msix index from that table based on "
raw_smp_processor_id".
If table is mapped correctly at probe time,  It is not possible to pick
entry of offline CPU.

Am I missing anything ?

If you can help me to understand why we need shared host tag for CPU
hotplug, I can try to frame some test case for possible reproduction.

>
> I just updated to include the change to have Scsi_Host.host_tagset in
> 4291f617a02b commit ("scsi: Add host and host template flag
> 'host_tagset'")
>
> megaraid sas support is not on the branch yet, but I think everything else
> required is. And it is mutable, so I'd clone it now if I were you - or
> just replace
> the required patch onto your v7 branch.

I am working on this.

>
> Thanks,
> John

  reply	other threads:[~2020-07-09 19:01 UTC|newest]

Thread overview: 123+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-10 17:29 [PATCH RFC v7 00/12] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs John Garry
2020-06-10 17:29 ` [PATCH RFC v7 01/12] blk-mq: rename BLK_MQ_F_TAG_SHARED as BLK_MQ_F_TAG_QUEUE_SHARED John Garry
2020-06-10 17:29 ` [PATCH RFC v7 02/12] blk-mq: rename blk_mq_update_tag_set_depth() John Garry
2020-06-11  2:57   ` Ming Lei
2020-06-11  8:26     ` John Garry
2020-06-23 11:25       ` John Garry
2020-06-23 14:23         ` Hannes Reinecke
2020-06-24  8:13           ` Kashyap Desai
2020-06-29 16:18             ` John Garry
2020-08-10 16:51           ` Kashyap Desai
2020-08-11  8:01             ` John Garry
2020-08-11 16:34               ` Kashyap Desai
2020-06-10 17:29 ` [PATCH RFC v7 03/12] blk-mq: Use pointers for blk_mq_tags bitmap tags John Garry
2020-06-10 17:29 ` [PATCH RFC v7 04/12] blk-mq: Facilitate a shared sbitmap per tagset John Garry
2020-06-11  3:37   ` Ming Lei
2020-06-11 10:09     ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 05/12] blk-mq: Record nr_active_requests per queue for when using shared sbitmap John Garry
2020-06-11  4:04   ` Ming Lei
2020-06-11 10:22     ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 06/12] blk-mq: Record active_queues_shared_sbitmap per tag_set " John Garry
2020-06-11 13:16   ` Hannes Reinecke
2020-06-11 14:22     ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a " John Garry
2020-06-11 13:19   ` Hannes Reinecke
2020-06-11 14:33     ` John Garry
2020-06-12  6:06       ` Hannes Reinecke
2020-06-29 15:32         ` About sbitmap_bitmap_show() and cleared bits (was Re: [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap) John Garry
2020-06-30  6:33           ` Hannes Reinecke
2020-06-30  7:30             ` John Garry
2020-06-30 11:36               ` John Garry
2020-06-30 14:55           ` Bart Van Assche
2020-07-13  9:41         ` [PATCH RFC v7 07/12] blk-mq: Add support in hctx_tags_bitmap_show() for a shared sbitmap John Garry
2020-07-13 12:20           ` Hannes Reinecke
2020-06-10 17:29 ` [PATCH RFC v7 08/12] scsi: Add template flag 'host_tagset' John Garry
2020-06-10 17:29 ` [PATCH RFC v7 09/12] scsi: hisi_sas: Switch v3 hw to MQ John Garry
2020-06-10 17:29 ` [PATCH RFC v7 10/12] megaraid_sas: switch fusion adapters " John Garry
2020-07-02 10:23   ` Kashyap Desai
2020-07-06  8:23     ` John Garry
2020-07-06  8:45       ` Hannes Reinecke
2020-07-06  9:26         ` John Garry
2020-07-06  9:40           ` Hannes Reinecke
2020-07-06 19:19       ` Kashyap Desai
2020-07-07  7:58         ` John Garry
2020-07-07 14:45           ` Kashyap Desai
2020-07-07 16:17             ` John Garry
2020-07-09 19:01               ` Kashyap Desai [this message]
2020-07-10  8:10                 ` John Garry
2020-07-13  7:55                   ` Kashyap Desai
2020-07-13  8:42                     ` John Garry
2020-07-19 19:07                       ` Kashyap Desai
2020-07-20  7:23                       ` Kashyap Desai
2020-07-20  9:18                         ` John Garry
2020-07-21  1:13                         ` Ming Lei
2020-07-21  6:53                           ` Kashyap Desai
2020-07-22  4:12                             ` Ming Lei
2020-07-22  5:30                               ` Kashyap Desai
2020-07-22  8:04                                 ` Ming Lei
2020-07-22  9:32                                   ` John Garry
2020-07-23 14:07                                     ` Ming Lei
2020-07-23 17:29                                       ` John Garry
2020-07-24  2:47                                         ` Ming Lei
2020-07-28  7:54                                           ` John Garry
2020-07-28  8:45                                             ` Ming Lei
2020-07-29  5:25                                               ` Kashyap Desai
2020-07-29 15:36                                                 ` Ming Lei
2020-07-29 18:31                                                   ` Kashyap Desai
2020-08-04  8:36                                                     ` Ming Lei
2020-08-04  9:27                                                       ` Kashyap Desai
2020-08-05  8:40                                                         ` Ming Lei
2020-08-06 10:25                                                           ` Kashyap Desai
2020-08-06 13:38                                                             ` Ming Lei
2020-08-06 14:37                                                               ` Kashyap Desai
2020-08-06 15:29                                                                 ` Ming Lei
2020-08-08 19:05                                                                   ` Kashyap Desai
2020-08-09  2:16                                                                     ` Ming Lei
2020-08-10 16:38                                                                       ` Kashyap Desai
2020-08-11  8:09                                                                         ` John Garry
2020-08-04 17:00                                               ` John Garry
2020-08-05  2:56                                                 ` Ming Lei
2020-07-28  8:01                                   ` Kashyap Desai
2020-07-08 11:31         ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 11/12] smartpqi: enable host tagset John Garry
2020-07-14 13:16   ` John Garry
2020-07-14 13:31     ` John Garry
2020-07-14 18:16       ` Don.Brace
2020-07-15  7:28         ` John Garry
2020-07-14 14:02     ` Hannes Reinecke
2020-08-18  8:33       ` John Garry
2020-06-10 17:29 ` [PATCH RFC v7 12/12] hpsa: enable host_tagset and switch to MQ John Garry
2020-07-14  7:37   ` John Garry
2020-07-14  7:41     ` Hannes Reinecke
2020-07-14  7:52       ` John Garry
2020-07-14  8:06         ` Ming Lei
2020-07-14  9:53           ` John Garry
2020-07-14 10:14             ` Ming Lei
2020-07-14 10:43               ` Hannes Reinecke
2020-07-14 10:19             ` Hannes Reinecke
2020-07-14 10:35               ` John Garry
2020-07-14 10:44               ` Ming Lei
2020-07-14 10:52                 ` John Garry
2020-07-14 12:04                   ` Ming Lei
2020-08-03 20:39         ` Don.Brace
2020-08-04  9:27           ` John Garry
2020-08-04 15:18             ` Don.Brace
2020-08-05 11:21               ` John Garry
2020-08-14 21:04                 ` Don.Brace
2020-08-17  8:00                   ` John Garry
2020-08-17 18:39                     ` Don.Brace
2020-08-18  7:14                       ` Hannes Reinecke
2020-07-16 16:14     ` Don.Brace
2020-07-16 19:45     ` Don.Brace
2020-07-17 10:11       ` John Garry
2020-06-11  3:07 ` [PATCH RFC v7 00/12] blk-mq/scsi: Provide hostwide shared tags for SCSI HBAs Ming Lei
2020-06-11  9:35   ` John Garry
2020-06-12 18:47     ` Kashyap Desai
2020-06-15  2:13       ` Ming Lei
2020-06-15  6:57         ` Kashyap Desai
2020-06-16  1:00           ` Ming Lei
2020-06-17 11:26             ` Kashyap Desai
2020-06-22  6:24               ` Hannes Reinecke
2020-06-23  0:55                 ` Ming Lei
2020-06-23 11:50                   ` Kashyap Desai
2020-06-23 12:11                   ` Kashyap Desai

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