On Wed, Oct 02, 2019 at 08:36:52AM -0600, Jens Axboe wrote: > On 10/2/19 3:56 AM, John Garry wrote: > > On 22/08/2019 18:39, John Garry wrote: > >> On 12/08/2019 14:43, 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! > >>> > >>> V2: > >>> - patch4 & patch 5 in V1 have been merged to block tree, so remove > >>> them > >>> - address comments from John Garry and Minwoo > >>> > >>> > >>> Ming Lei (5): > >>> blk-mq: add new state of BLK_MQ_S_INTERNAL_STOPPED > >>> blk-mq: add blk-mq flag of BLK_MQ_F_NO_MANAGED_IRQ > >>> blk-mq: stop to handle IO before hctx's all CPUs become offline > >>> blk-mq: re-submit IO in case that hctx is dead > >>> blk-mq: handle requests dispatched from IO scheduler in case that hctx > >>> is dead > >> > >> Hi Ming, > >> > >> This looks to fix the hotplug issue for me. > >> > >> Previously I could manufacture a scenario while running fio where I got > >> IO timeouts, like this: > >> > >> root@(none)$ echo 0 > ./sys/devices/system/cpu/cpu0/online > >> [ 296.897627] process 891 (fio) no longer affine to cpu0 > >> [ 296.898488] process 893 (fio) no longer affine to cpu0 > >> [ 296.910270] process 890 (fio) no longer affine to cpu0 > >> [ 296.927322] IRQ 775: no longer affine to CPU0 > >> [ 296.932762] CPU0: shutdown > >> [ 296.935469] psci: CPU0 killed. > >> root@(none)$ [ 326.971962] sas: Enter sas_scsi_recover_host busy: 61 > >> failed: 61 > >> [ 326.977978] sas: sas_scsi_find_task: aborting task 0x00000000e2cdc79b > >> root@(none)$ [ 333.047964] hisi_sas_v3_hw 0000:74:02.0: internal task > >> abort: timeout and not done. > >> [ 333.055616] hisi_sas_v3_hw 0000:74:02.0: abort task: internal abort (-5) > >> [ 333.062306] sas: sas_scsi_find_task: querying task 0x00000000e2cdc79b > >> [ 333.068776] sas: sas_scsi_find_task: task 0x00000000e2cdc79b not at LU > >> [ 333.075295] sas: task 0x00000000e2cdc79b is not at LU: I_T recover > >> [ 333.081464] sas: I_T nexus reset for dev 5000c500a7b95a49 > >> > >> Please notice the 30-second delay for the SCSI IO timeout. > >> > >> And now I don't see it; here's a sample for irq shutdown: > >> root@(none)$ echo 0 > ./sys/devices/system/cpu/cpu0/online > >> [ 344.608148] process 849 (fio) no longer affine to cpu0 > >> [ 344.608639] process 848 (fio) no longer affine to cpu0 > >> [ 344.609454] process 850 (fio) no longer affine to cpu0 > >> [ 344.643481] process 847 (fio) no longer affine to cpu0 > >> [ 346.213842] IRQ 775: no longer affine to CPU0 > >> [ 346.219712] CPU0: shutdown > >> [ 346.222425] psci: CPU0 killed. > >> > >> Please notice the ~1.5s pause, which would be the queue draining. > >> > >> So FWIW: > >> Tested-by: John Garry <john.garry@xxxxxxxxxx> > >> > >> JFYI, I tested on 5.3-rc5 and cherry-picked > >> https://github.com/ming1/linux/commit/0d2cd3c99bb0fe81d2c0ca5d68e02bdc4521d4d6 > >> and "blk-mq: add callback of .cleanup_rq". > >> > >> Cheers, > >> John > > > > Hi Jens, > > > > I don't mean to be pushy, but can we consider to get these patches from > > Ming merged? > > > > As above, I tested on my SCSI driver and it works. I also tested on an > > NVMe disk, and it solves the condition which generates this message: > > root@(none)$ echo 0 > /sys/devices/system/cpu/cpu2/online > > [ 465.635960] CPU2: shutdown > > [ 465.638662] psci: CPU2 killed. > > [ 111.381653] nvme nvme0: I/O 705 QID 18 timeout, completion polled > > > > (that's on top off v5.4-rc1) > > Ming, can you repost the series? It has been resent out just now. Thanks, Ming
