On Wed, Jan 11, 2017 at 1:10 PM, Dexuan Cui <decui@xxxxxxxxxxxxx> wrote: >> From: Dexuan Cui >> Sent: Tuesday, December 20, 2016 11:41 >> To: 'Jens Axboe' <axboe@xxxxxx>; Ming Lei <ming.lei@xxxxxxxxxxxxx> >> Cc: Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; linux-block >> <linux-block@xxxxxxxxxxxxxxx>; Christoph Hellwig <hch@xxxxxxxxxxxxx>; >> Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>; Keith Busch >> <keith.busch@xxxxxxxxx>; Hannes Reinecke <hare@xxxxxxx>; Mike Christie >> <mchristi@xxxxxxxxxx>; Martin K. Petersen <martin.petersen@xxxxxxxxxx>; >> Toshi Kani <toshi.kani@xxxxxxx>; Dan Williams <dan.j.williams@xxxxxxxxx>; >> Damien Le Moal <damien.lemoal@xxxxxxxx> >> Subject: RE: [PATCH] block: loose check on sg gap >> >> > From: Jens Axboe [mailto:axboe@xxxxxx] >> > Sent: Tuesday, December 20, 2016 10:31 >> > To: Ming Lei <ming.lei@xxxxxxxxxxxxx> >> > Cc: Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>; linux-block >> <linux- >> > block@xxxxxxxxxxxxxxx>; Christoph Hellwig <hch@xxxxxxxxxxxxx>; Dexuan >> Cui >> > <decui@xxxxxxxxxxxxx>; Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>; Keith >> Busch >> > <keith.busch@xxxxxxxxx>; Hannes Reinecke <hare@xxxxxxx>; Mike Christie >> > <mchristi@xxxxxxxxxx>; Martin K. Petersen >> <martin.petersen@xxxxxxxxxx>; >> > Toshi Kani <toshi.kani@xxxxxxx>; Dan Williams >> <dan.j.williams@xxxxxxxxx>; >> > Damien Le Moal <damien.lemoal@xxxxxxxx> >> > Subject: Re: [PATCH] block: loose check on sg gap >> > >> > On 12/19/2016 07:07 PM, Ming Lei wrote: >> > > On Sun, Dec 18, 2016 at 12:49 AM, Jens Axboe <axboe@xxxxxx> wrote: >> > >> On 12/17/2016 03:49 AM, Ming Lei wrote: >> > >>> If the last bvec of the 1st bio and the 1st bvec of the next >> > >>> bio are contineous physically, and the latter can be merged >> > >>> to last segment of the 1st bio, we should think they don't >> > >>> violate sg gap(or virt boundary) limit. >> > >>> >> > >>> Both Vitaly and Dexuan reported lots of unmergeable small bios >> > >>> are observed when running mkfs on Hyper-V virtual storage, and >> > >>> performance becomes quite low, so this patch is figured out for >> > >>> fixing the performance issue. >> > >>> >> > >>> The same issue should exist on NVMe too sine it sets virt boundary >> too. >> > >> >> > >> It looks pretty reasonable to me. I'll queue it up for some testing, >> > >> changes like this always make me a little nervous. >> > > >> > > Understood. >> > > >> > > But given it is still in early stage of 4.10 cycle, seems fine to expose >> > > it now, and we should have enough time to fix it if there might be >> > > regressions. >> > > >> > > BTW, it passes my xfstest(ext4) over sata/NVMe. >> > >> > It's been fine here in testing, too. I'm not worried about performance >> > regressions, those we can always fix. Merging makes me worried about >> > corruption, and those regressions are much worse. >> > >> > Any reason we need to rush this? I'd be more comfortable pushing this to >> > 4.11, unless there are strong reasons this should make 4.10. >> > >> > -- >> > Jens Axboe >> >> Hi Jens, >> >> As far as I know, the patch is important to popular Linux distros, >> e.g. at least Ubuntu 14.04.5, 16.x and RHEL 7.3, when they run on >> Hyper-V/Azure, because they can suffer from a pretty bad >> throughput/latency >> in some cases, e.g. mkfs.ext4 for a 100GB partition can take 8 minutes, but >> with the patch, it only takes 1 second. >> >> -- Dexuan > > Hi Ming, Jens, > Did you find any issue later when testing with the patch? > > May I know if it's possible to have it in 4.10 considering the above impact? > > Is it on some temporary branch of linux-block.git? Looks not. Dexuan, Jens has said that this patch may land v4.11, so just wait a release and let it expose into more tests. Thanks, Ming -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
