linux-kernel - Re: [Question] Should direct reclaim time be bounded?

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Message-ID: <20190710194403.GR29695@dhcp22.suse.cz>
Date:   Wed, 10 Jul 2019 21:44:03 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Mike Kravetz <mike.kravetz@...cle.com>
Cc:     Hillf Danton <hdanton@...a.com>, Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...e.de>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Johannes Weiner <hannes@...xchg.org>
Subject: Re: [Question] Should direct reclaim time be bounded?

On Wed 10-07-19 11:42:40, Mike Kravetz wrote:
[...]
> As Michal suggested, I'm going to do some testing to see what impact
> dropping the __GFP_RETRY_MAYFAIL flag for these huge page allocations
> will have on the number of pages allocated.

Just to clarify. I didn't mean to drop __GFP_RETRY_MAYFAIL from the
allocation request. I meant to drop the special casing of the flag in
should_continue_reclaim. I really have hard time to argue for this
special casing TBH. The flag is meant to retry harder but that shouldn't
be reduced to a single reclaim attempt because that alone doesn't really
help much with the high order allocation. It is more about compaction to
be retried harder.
-- 
Michal Hocko
SUSE Labs