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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH 2/2] mm: oom: terminate the oom_evaluate_task() loop early Content-Language: en-US To: Michal Hocko CC: , , , , References: <20230814063428.4111206-1-zhangpeng362@huawei.com> <20230814063428.4111206-3-zhangpeng362@huawei.com> From: "zhangpeng (AS)" In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.160] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemm600020.china.huawei.com (7.193.23.147) X-CFilter-Loop: Reflected X-Stat-Signature: spaea86igrfepjzxstqdpu1r7zud4y5q X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 20B28C0014 X-Rspam-User: X-HE-Tag: 1692176224-718283 X-HE-Meta: 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 S8waSeQA 6wyp2+IagP1zZh/aiVmPpJ2kI6lRH0SJlt+2ZUTxe7eJiRi/3NnBmhbddg4y9Kkx64LvJDpx5NpjZ27JfX1JSxxNcotaObX7ld8oCGUOQUSQIXZTK64ALqTexpcHd6zQaoTKa666CfySDfEfyd2iOGlHNZZYgu53ZFAwu7O2LMe3ii0z+C/I/Ki+kl12NqLBDwCKK X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/8/16 14:48, Michal Hocko wrote: > On Mon 14-08-23 14:34:28, Peng Zhang wrote: >> From: ZhangPeng >> >> If task is allocating a lot of memory and has been marked to be killed >> first, then it gets the highest score (LONG_MAX). Therefore, there is no >> need to continue to calculate the points of other tasks. Just terminate >> the oom_evaluate_task() loop early, when the task with the highest score >> is found. By doing this, we can get some performance gains in >> select_bad_process(). > The point of evaluating all tasks is that there might be pre-existing > oom victim still being torn down. If you cut this short you might kill > more tasks than necessary. Indeed. Thanks for your feedback. > So I do not think we want this patch. >> To implement it, the return value of oom_evaluate_task() is modified. >> When the task with the highest score is found (points == LONG_MAX), >> oom_evaluate_task() will return 1 and the loop will terminate early. >> >> Signed-off-by: ZhangPeng >> --- >> mm/oom_kill.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/mm/oom_kill.c b/mm/oom_kill.c >> index 10f7826c4035..02d11ae043aa 100644 >> --- a/mm/oom_kill.c >> +++ b/mm/oom_kill.c >> @@ -346,6 +346,8 @@ static int oom_evaluate_task(struct task_struct *task, void *arg) >> get_task_struct(task); >> oc->chosen = task; >> oc->chosen_points = points; >> + if (points == LONG_MAX) >> + return 1; >> next: >> return 0; >> abort: >> -- >> 2.25.1 -- Best Regards, Peng