From: Zhongkun He <hezhongkun.hzk@bytedance.com>
To: Michal Hocko <mhocko@suse.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: Thu, 13 Oct 2022 21:42:30 +0800 [thread overview]
Message-ID: <a401c9a3-026c-9695-d339-24347965cd20@bytedance.com> (raw)
In-Reply-To: <Y0gP9i8KZKt4/EcG@dhcp22.suse.cz>
> On Thu 13-10-22 20:50:48, Zhongkun He wrote:
>>>> Hi Michal
>>>>
>>>> Could we try to change the MPOL_F_SHARED flag to MPOL_F_STATIC to
>>>> mark static mempolicy which cannot be freed, and mpol_needs_cond_ref
>>>> can use MPOL_F_STATIC to avoid freeing the static mempolicy.
>>>
>>> Wouldn't it make more sense to get rid of a different treatment and
>>> treat all memory policies the same way?
>>
>> I found a case, not sure if it makes sense. If there is no policy
>> in task->mempolicy, the use of atomic_{inc,dec} can be skiped
>> according to MPOL_F_STATIC. Atomic_{inc,dec} in hot path may reduces
>> performance.
>
> I would start with a simple conversion and do any potential
> optimizations on top of that based on actual numbers. Maybe we can
> special case default_policy to avoid reference counting a default (no
> policy case). A simple check for pol == &default_policy should be
> negligible.
Got it, thanks for your reply and suggestions.
next prev parent reply other threads:[~2022-10-13 13:42 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
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 [this message]
2022-10-12 4:16 ` Bagas Sanjaya
2022-10-12 8:18 ` [External] " Zhongkun He
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