From: Michal Hocko <mhocko@suse.com>
To: Zhongkun He <hezhongkun.hzk@bytedance.com>
Cc: corbet@lwn.net, akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
linux-doc@vger.kernel.org, wuyun.abel@bytedance.com
Subject: Re: [External] Re: [RFC] mm: add new syscall pidfd_set_mempolicy()
Date: Wed, 12 Oct 2022 14:15:10 +0200 [thread overview]
Message-ID: <Y0avztF7QU8P/OoB@dhcp22.suse.cz> (raw)
In-Reply-To: <a0421769-c2b9-d59a-0358-3cc84b2cb2bd@bytedance.com>
On Wed 12-10-22 19:22:21, Zhongkun He wrote:
> >
> > Yes, this will require some refactoring and one potential way is to make
> > mpol ref counting unconditional. The conditional ref. counting has
> > already caused issues in the past and the code is rather hard to follow
> > anyway. I am not really sure this optimization is worth it.
> >
> > Another option would be to block the pidfd side of things on completion
> > which would wake it up from the task_work context but I would rather
> > explore the ref counting approach first and only if this is proven to be
> > too expensive to go with hacks like this.
>
> Hi Michal
>
> The counting approach means executing mpol_get/put() when start/finish using
> mempolicy,right?
We already do that via mpol_{get,put} but there are cases where the
reference counting is ignored because it cannot be freed and also mpol_cond_put
resp. open coded versions of mpol_needs_cond_ref.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2022-10-12 12:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-10 9:48 Zhongkun He
2022-10-10 16:22 ` Frank van der Linden
2022-10-11 15:00 ` Michal Hocko
2022-10-11 17:22 ` Frank van der Linden
2022-10-11 19:29 ` Michal Hocko
2022-10-12 3:14 ` Abel Wu
2022-10-12 12:34 ` Vinicius Petrucci
2022-10-12 13:07 ` Michal Hocko
2022-10-12 13:23 ` Michal Hocko
2022-10-12 16:51 ` Frank van der Linden
2022-10-11 14:57 ` Michal Hocko
2022-10-12 7:55 ` [External] " Zhongkun He
2022-10-12 9:02 ` Michal Hocko
2022-10-12 11:22 ` Zhongkun He
2022-10-12 12:15 ` Michal Hocko [this message]
2022-10-13 10:44 ` Zhongkun He
2022-10-13 11:26 ` Michal Hocko
2022-10-13 12:50 ` Zhongkun He
2022-10-13 13:17 ` Michal Hocko
2022-10-13 13:42 ` Zhongkun He
2022-10-12 4:16 ` Bagas Sanjaya
2022-10-12 8:18 ` [External] " Zhongkun He
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