From: Yafang Shao <laoar.shao@gmail.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Michal Hocko <mhocko@suse.com>,
Linux MM <linux-mm@kvack.org>
Subject: Re: [PATCH] mm: print a warning once the vm dirtiness settings is illogical
Date: Sun, 26 Nov 2017 16:46:29 +0800 [thread overview]
Message-ID: <CALOAHbAgh0egRJk7ME_YBzon9ED9jL94vi4aw19bbpZVuUA+aQ@mail.gmail.com> (raw)
In-Reply-To: <201711261703.HDI52138.JSFVOFOtHLMOFQ@I-love.SAKURA.ne.jp>
2017-11-26 16:03 GMT+08:00 Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>:
> Yafang Shao wrote:
>> >> I have also verified your test code on my machine, but can not find
>> >> this message.
>> >>
>> >
>> > Not always printed. It is timing dependent.
>> >
>>
>> I will try and analysis why this happen.
>>
> I see.
>
> Here is dump of variables. Always mostly 0 when this happens.
>
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -434,7 +434,8 @@ static void domain_dirty_limits(struct dirty_throttle_control *dtc)
> bg_thresh = (bg_ratio * available_memory) / PAGE_SIZE;
>
> if (unlikely(bg_thresh >= thresh)) {
> - pr_warn("vm direct limit must be set greater than background limit.\n");
> + pr_warn("vm direct limit must be set greater than background limit. bg_thresh=%lu thresh=%lu bg_bytes=%lu bytes=%lu bg_ratio=%lu ratio=%lu gdtc=%p gdtc->vail=%lu vm_dirty_bytes=%lu dirty_background_bytes=%lu\n",
> + bg_thresh, thresh, bg_bytes, bytes, bg_ratio, ratio, gdtc, gdtc ? gdtc->avail : 0UL, vm_dirty_bytes, dirty_background_bytes);
> bg_thresh = thresh / 2;
> }
You could print dtc->avail as well.
Seems bg_thresh and thresh are not so acurate as they are interger
other than float.
Should find a smart way to fix it.
>
> [ 259.641324] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 317.798913] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 317.798935] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 317.976210] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 417.781194] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 466.322615] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 466.322618] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 466.497893] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
> [ 466.504687] vm direct limit must be set greater than background limit. bg_thresh=0 thresh=0 bg_bytes=0 bytes=0 bg_ratio=409 ratio=1228 gdtc= (null) gdtc->vail=0 vm_dirty_bytes=0 dirty_background_bytes=0
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next prev parent reply other threads:[~2017-11-26 8:46 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-28 9:54 [PATCH] mm: print a warning once the vm dirtiness settings is illogical Yafang Shao
2017-11-25 16:05 ` Tetsuo Handa
2017-11-26 2:24 ` Yafang Shao
2017-11-26 2:42 ` Tetsuo Handa
2017-11-26 4:32 ` Yafang Shao
2017-11-26 8:03 ` Tetsuo Handa
2017-11-26 8:27 ` Yafang Shao
2017-11-26 8:46 ` Yafang Shao [this message]
2017-11-26 10:38 ` Tetsuo Handa
2017-11-27 8:06 ` Yafang Shao
2017-11-27 8:21 ` Michal Hocko
2017-11-27 8:29 ` Yafang Shao
2017-11-27 8:32 ` Yafang Shao
2017-11-27 8:37 ` Michal Hocko
2017-11-27 8:49 ` Yafang Shao
2017-11-27 8:52 ` Michal Hocko
2017-11-27 8:54 ` Yafang Shao
2017-11-27 9:04 ` Michal Hocko
2017-11-27 9:08 ` Yafang Shao
2017-11-27 8:34 ` Michal Hocko
2017-11-27 9:19 ` [PATCH] Revert "mm/page-writeback.c: print a warning if the vm dirtiness settings are illogical" (was: Re: [PATCH] mm: print a warning once the vm dirtiness settings is illogical) Michal Hocko
2017-11-28 3:11 ` Yafang Shao
2017-11-28 6:12 ` Yafang Shao
2017-11-28 7:45 ` Michal Hocko
2017-11-28 7:52 ` Yafang Shao
2017-11-28 9:43 ` Yafang Shao
2017-11-28 9:45 ` Michal Hocko
2017-11-28 10:09 ` Jan Kara
2017-11-28 10:16 ` Yafang Shao
2017-11-28 10:25 ` Jan Kara
2017-11-28 10:33 ` Yafang Shao
2017-11-28 10:41 ` Jan Kara
2017-11-28 10:44 ` Yafang Shao
2017-11-28 10:37 ` Jan Kara
2017-11-28 10:48 ` Michal Hocko
2017-11-28 11:05 ` Yafang Shao
2017-11-28 11:54 ` Michal Hocko
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