linux-kernel - Re: [PATCH] cfq-iosched: Reduce linked group count upon group destruction

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

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <4E37A638.2020304@fusionio.com>
Date:	Tue, 2 Aug 2011 09:24:40 +0200
From:	Jens Axboe <jaxboe@...ionio.com>
To:	Vivek Goyal <vgoyal@...hat.com>
CC:	linux kernel mailing list <linux-kernel@...r.kernel.org>,
	"Israel G. Lugo" <israel.lugo@...osys.com>
Subject: Re: [PATCH] cfq-iosched: Reduce linked group count upon group  destruction

On 2011-08-01 20:47, Vivek Goyal wrote:
> CFQ keeps track of number of groups which are linked on blkcg->blkg_list.
> This is useful to avoid races between queue exit and cgroup exit code
> paths. So if at the request queue exit time linked group count is not
> zero, that means there are some group out there which is yet to be
> deleted under rcu read period and queue exit code should wait for
> on rcu period.
> 
> In my previous patch I forgot to decrease the number of group count.
> So in current form, we nr_blkcg_linked_grps is always non-zero and
> we will always wait one rcu period (if BLK_CGROUP=y). The side effect
> of this is that it can increase boot time. I am surprised, nobody
> complained so far.

Thanks Vivek, applied.

-- 
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/