From: Vlastimil Babka <vbabka@suse.cz>
To: Mike Kravetz <mike.kravetz@oracle.com>, Michal Hocko <mhocko@kernel.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [Question] Should direct reclaim time be bounded?
Date: Wed, 24 Apr 2019 16:35:37 +0200 [thread overview]
Message-ID: <04329fea-cd34-4107-d1d4-b2098ebab0ec@suse.cz> (raw)
In-Reply-To: <eac582cf-2f76-4da1-1127-6bb5c8c959e4@oracle.com>
On 4/23/19 6:39 PM, Mike Kravetz wrote:
>> That being said, I do not think __GFP_RETRY_MAYFAIL is wrong here. It
>> looks like there is something wrong in the reclaim going on.
>
> Ok, I will start digging into that. Just wanted to make sure before I got
> into it too deep.
>
> BTW - This is very easy to reproduce. Just try to allocate more huge pages
> than will fit into memory. I see this 'reclaim taking forever' behavior on
> v5.1-rc5-mmotm-2019-04-19-14-53. Looks like it was there in v5.0 as well.
I'd suspect this in should_continue_reclaim():
/* Consider stopping depending on scan and reclaim activity */
if (sc->gfp_mask & __GFP_RETRY_MAYFAIL) {
/*
* For __GFP_RETRY_MAYFAIL allocations, stop reclaiming if the
* full LRU list has been scanned and we are still failing
* to reclaim pages. This full LRU scan is potentially
* expensive but a __GFP_RETRY_MAYFAIL caller really wants to succeed
*/
if (!nr_reclaimed && !nr_scanned)
return false;
And that for some reason, nr_scanned never becomes zero. But it's hard
to figure out through all the layers of functions :/
next prev parent reply other threads:[~2019-04-24 14:39 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-23 4:07 [Question] Should direct reclaim time be bounded? Mike Kravetz
2019-04-23 7:19 ` Michal Hocko
2019-04-23 16:39 ` Mike Kravetz
2019-04-24 14:35 ` Vlastimil Babka [this message]
2019-06-28 18:20 ` Mike Kravetz
2019-07-01 8:59 ` Mel Gorman
2019-07-02 3:15 ` Mike Kravetz
2019-07-03 9:43 ` Mel Gorman
2019-07-03 23:54 ` Mike Kravetz
2019-07-04 11:09 ` Michal Hocko
2019-07-04 15:11 ` Mike Kravetz
2019-07-10 18:42 ` Mike Kravetz
2019-07-10 19:44 ` Michal Hocko
2019-07-10 23:36 ` Mike Kravetz
2019-07-11 7:12 ` Michal Hocko
2019-07-12 9:49 ` Mel Gorman
[not found] <20190712054732.7264-1-hdanton@sina.com>
2019-07-13 1:11 ` Mike Kravetz
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