From: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: linux-kernel@vger.kernel.org, jens.axboe@oracle.com,
nauman@google.com, lizf@cn.fujitsu.com, ryov@valinux.co.jp,
fernando@oss.ntt.co.jp, taka@valinux.co.jp, jmoyer@redhat.com,
m-ikeda@ds.jp.nec.com, czoccolo@gmail.com, Alan.Brunelle@hp.com
Subject: Re: [PATCH 1/4] cfq-iosced: Remove the check for same cfq group from allow_merge
Date: Thu, 17 Dec 2009 17:26:03 +0800 [thread overview]
Message-ID: <4B29F92B.2040602@cn.fujitsu.com> (raw)
In-Reply-To: <1261003980-10115-2-git-send-email-vgoyal@redhat.com>
Vivek Goyal wrote:
> o allow_merge() already checks if submitting task is pointing to same cfqq
> as rq has been queued in. If everything is fine, we should not be having
> a task in one cgroup and having a pointer to cfqq in other cgroup.
>
> Well I guess in some situations it can happen and that is, when a random
> IO queue has been moved into root cgroup for group_isolation=0. In
> this case, tasks's cgroup/group is different from where actually cfqq is,
> but this is intentional and in this case merging should be allowed.
>
> The second situation is where due to close cooperator patches, multiple
> processes can be sharing a cfqq. If everything implemented right, we should
> not end up in a situation where tasks from different processes in different
> groups are sharing the same cfqq as we allow merging of cooperating queues
> only if they are in same group.
>
> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
next prev parent reply other threads:[~2009-12-17 9:30 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-16 22:52 [RFC] CFQ group scheduling structure organization Vivek Goyal
2009-12-16 22:52 ` [PATCH 1/4] cfq-iosced: Remove the check for same cfq group from allow_merge Vivek Goyal
2009-12-17 9:26 ` Gui Jianfeng [this message]
2009-12-16 22:52 ` [PATCH 2/4] cfq-iosched: Get rid of nr_groups Vivek Goyal
2009-12-17 9:26 ` Gui Jianfeng
2009-12-16 22:52 ` [PATCH 3/4] cfq-iosched: Remove prio_change logic for workload selection Vivek Goyal
2009-12-17 9:20 ` Gui Jianfeng
2009-12-18 15:17 ` Vivek Goyal
2009-12-20 4:19 ` Gui Jianfeng
2009-12-17 11:49 ` Corrado Zoccolo
2009-12-16 22:53 ` [PATCH 4/4] cfq-iosched: Implement system wide RT and IDLE groups Vivek Goyal
2009-12-16 23:14 ` [RFC] CFQ group scheduling structure organization Nauman Rafique
2009-12-16 23:24 ` Vivek Goyal
2009-12-17 10:17 ` Gui Jianfeng
2009-12-18 15:21 ` Vivek Goyal
2009-12-17 11:41 ` Corrado Zoccolo
2009-12-17 23:58 ` Munehiro Ikeda
2009-12-18 16:01 ` Vivek Goyal
2009-12-21 12:16 ` Jens Axboe
2009-12-21 14:42 ` Vivek Goyal
2009-12-18 15:49 ` Vivek Goyal
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