lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 4 May 2015 14:35:33 -0600 From: Jens Axboe <axboe@...com> To: Shaohua Li <shli@...com> CC: Jeff Moyer <jmoyer@...hat.com>, <linux-kernel@...r.kernel.org>, <hch@....de>, <neilb@...e.de> Subject: Re: [PATCH 4/5] blk-mq: do limited block plug for multiple queue case On 05/04/2015 02:33 PM, Shaohua Li wrote: > On Mon, May 04, 2015 at 01:46:49PM -0600, Jens Axboe wrote: >> On 05/04/2015 01:40 PM, Shaohua Li wrote: >>> On Fri, May 01, 2015 at 04:16:04PM -0400, Jeff Moyer wrote: >>>> Shaohua Li <shli@...com> writes: >>>> >>>>> plug is still helpful for workload with IO merge, but it can be harmful >>>>> otherwise especially with multiple hardware queues, as there is >>>>> (supposed) no lock contention in this case and plug can introduce >>>>> latency. For multiple queues, we do limited plug, eg plug only if there >>>>> is request merge. If a request doesn't have merge with following >>>>> request, the requet will be dispatched immediately. >>>>> >>>>> This also fixes a bug. If we directly issue a request and it fails, we >>>>> use blk_mq_merge_queue_io(). But we already assigned bio to a request in >>>>> blk_mq_bio_to_request. blk_mq_merge_queue_io shouldn't run >>>>> blk_mq_bio_to_request again. >>>> >>>> Good catch. Might've been better to split that out first for easy >>>> backport to stable kernels, but I won't hold you to that. >>> >>> It's not a severe bug, but I don't mind. Jens, please let me know if I >>> should split the patch into 2 patches. >> >> I don't care that much for this particular case. But since one/more >> of the others need respin anyway, might be prudent to split it up in >> any case. > > ok, done. I'll repost the patch 4/5. Please let me know if I should > repost 1-3. That's fine, I'll grab 1-3 as-is. Thanks! -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists