linux-kernel - Re: [PATCH 39/41] kernel/fork: throttle call_rcu() calls in vm_area

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Message-ID: <Y8bFdB47JT/luMld@dhcp22.suse.cz>
Date:   Tue, 17 Jan 2023 16:57:40 +0100
From:   Michal Hocko <mhocko@...e.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, michel@...pinasse.org,
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Subject: Re: [PATCH 39/41] kernel/fork: throttle call_rcu() calls in
 vm_area_free

On Mon 09-01-23 12:53:34, Suren Baghdasaryan wrote:
> call_rcu() can take a long time when callback offloading is enabled.
> Its use in the vm_area_free can cause regressions in the exit path when
> multiple VMAs are being freed.

What kind of regressions.

> To minimize that impact, place VMAs into
> a list and free them in groups using one call_rcu() call per group.

Please add some data to justify this additional complexity.
-- 
Michal Hocko
SUSE Labs