From: Ming Lei <ming.lei@redhat.com>
To: John Garry <john.garry@huawei.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Bart Van Assche <bvanassche@acm.org>,
Hannes Reinecke <hare@suse.com>, Christoph Hellwig <hch@lst.de>,
Thomas Gleixner <tglx@linutronix.de>,
Keith Busch <keith.busch@intel.com>
Subject: Re: [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug
Date: Wed, 16 Oct 2019 20:07:30 +0800 [thread overview]
Message-ID: <20191016120729.GB5515@ming.t460p> (raw)
In-Reply-To: <d30420d7-74d9-4417-1bbe-8113848e74fa@huawei.com>
On Wed, Oct 16, 2019 at 09:58:27AM +0100, John Garry wrote:
> On 14/10/2019 02:50, Ming Lei wrote:
> > Hi,
> >
> > Thomas mentioned:
> > "
> > That was the constraint of managed interrupts from the very beginning:
> >
> > The driver/subsystem has to quiesce the interrupt line and the associated
> > queue _before_ it gets shutdown in CPU unplug and not fiddle with it
> > until it's restarted by the core when the CPU is plugged in again.
> > "
> >
> > But no drivers or blk-mq do that before one hctx becomes dead(all
> > CPUs for one hctx are offline), and even it is worse, blk-mq stills tries
> > to run hw queue after hctx is dead, see blk_mq_hctx_notify_dead().
> >
> > This patchset tries to address the issue by two stages:
> >
> > 1) add one new cpuhp state of CPUHP_AP_BLK_MQ_ONLINE
> >
> > - mark the hctx as internal stopped, and drain all in-flight requests
> > if the hctx is going to be dead.
> >
> > 2) re-submit IO in the state of CPUHP_BLK_MQ_DEAD after the hctx becomes dead
> >
> > - steal bios from the request, and resubmit them via generic_make_request(),
> > then these IO will be mapped to other live hctx for dispatch
> >
> > Please comment & review, thanks!
> >
> > John, I don't add your tested-by tag since V3 have some changes,
> > and I appreciate if you may run your test on V3.
>
> Hi Ming,
>
> So I got around to doing some testing. The good news is that issue which we
> were experiencing in v3 series seems to have has gone away - alot more
> stable.
>
> However, unfortunately, I did notice some SCSI timeouts:
>
> 15508.615074] CPU2: shutdown
> [15508.617778] psci: CPU2 killed.
> [15508.651220] CPU1: shutdown
> [15508.653924] psci: CPU1 killed.
> [15518.406229] sas: Enter sas_scsi_recover_host busy: 63 failed: 63
> Jobs: 1 (f=1): [R] [0.0% done] [0[15518.412239] sas: sas_scsi_find_task:
> aborting task 0x00000000a7159744
> KB/0KB/0KB /s] [0/0/0 iops] [eta [15518.421708] sas:
> sas_eh_handle_sas_errors: task 0x00000000a7159744 is done
> [15518.431266] sas: sas_scsi_find_task: aborting task 0x00000000d39731eb
> [15518.442539] sas: sas_eh_handle_sas_errors: task 0x00000000d39731eb is
> done
> [15518.449407] sas: sas_scsi_find_task: aborting task 0x000000009f77c9bd
> [15518.455899] sas: sas_eh_handle_sas_errors: task 0x000000009f77c9bd is
> done
>
> A couple of things to note:
> - I added some debug prints in blk_mq_hctx_drain_inflight_rqs() for when
> inflights rqs !=0, and I don't see them for this timeout
> - 0 datarate reported from fio
>
> I'll have a look...
What is the output of the following command?
(cd /sys/kernel/debug/block/$SAS_DISK && find . -type f -exec grep -aH . {} \;)
Thanks,
Ming
next prev parent reply other threads:[~2019-10-16 12:07 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 1:50 [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug Ming Lei
2019-10-14 1:50 ` [PATCH V4 1/5] blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED Ming Lei
2019-10-14 1:50 ` [PATCH V4 2/5] blk-mq: prepare for draining IO when hctx's all CPUs are offline Ming Lei
2019-10-14 1:50 ` [PATCH V4 3/5] blk-mq: stop to handle IO and drain IO before hctx becomes dead Ming Lei
2019-11-28 9:29 ` John Garry
2019-10-14 1:50 ` [PATCH V4 4/5] blk-mq: re-submit IO in case that hctx is dead Ming Lei
2019-10-14 1:50 ` [PATCH V4 5/5] blk-mq: handle requests dispatched from IO scheduler " Ming Lei
2019-10-16 8:58 ` [PATCH V4 0/5] blk-mq: improvement on handling IO during CPU hotplug John Garry
2019-10-16 12:07 ` Ming Lei [this message]
2019-10-16 16:19 ` John Garry
[not found] ` <55a84ea3-647d-0a76-596c-c6c6b2fc1b75@huawei.com>
2019-10-20 10:14 ` Ming Lei
2019-10-21 9:19 ` John Garry
2019-10-21 9:34 ` Ming Lei
2019-10-21 9:47 ` John Garry
2019-10-21 10:24 ` Ming Lei
2019-10-21 11:49 ` John Garry
2019-10-21 12:53 ` Ming Lei
2019-10-21 14:02 ` John Garry
2019-10-22 0:16 ` Ming Lei
2019-10-22 11:19 ` John Garry
2019-10-22 13:45 ` Ming Lei
2019-10-25 16:33 ` John Garry
2019-10-28 10:42 ` Ming Lei
2019-10-28 11:55 ` John Garry
2019-10-29 1:50 ` Ming Lei
2019-10-29 9:22 ` John Garry
2019-10-29 10:05 ` Ming Lei
2019-10-29 17:54 ` John Garry
2019-10-31 16:28 ` John Garry
2019-11-28 1:09 ` chenxiang (M)
2019-11-28 2:02 ` Ming Lei
2019-11-28 10:45 ` John Garry
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