From: Christopher Lameter <cl@linux.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@kernel.org>,
Mikulas Patocka <mpatocka@redhat.com>,
Mike Snitzer <snitzer@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Pekka Enberg <penberg@kernel.org>,
linux-mm@kvack.org, dm-devel@redhat.com,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] SLUB: Do not fallback to mininum order if __GFP_NORETRY is set
Date: Mon, 23 Apr 2018 17:41:06 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.20.1804231738020.3811@nuc-kabylake> (raw)
In-Reply-To: <26580de4-70b5-90f7-b3b9-22f57ba38843@suse.cz>
On Sat, 21 Apr 2018, Vlastimil Babka wrote:
> > The problem is that SLUB does not honor GFP_NORETRY. The semantics of
> > GFP_NORETRY are not followed.
>
> The caller might want SLUB to try hard to get that high-order page that
> will minimize memory waste (e.g. 2MB page for 3 640k objects), and
> __GFP_NORETRY will kill the effort on allocating that high-order page.
Well yes since *_NORETRY says that fallbacks are acceptable.
> Thus, using __GPF_NORETRY for "please give me a space-optimized object,
> or nothing (because I have a fallback that's better than wasting memory,
> e.g. by using 1MB page for 640kb object)" is not ideal.
>
> Maybe __GFP_RETRY_MAYFAIL is a better fit? Or perhaps indicate this
> situation to SLUB with e.g. __GFP_COMP, although that's rather ugly?
Yuck. None of that sounds like an intuitive approach.
prev parent reply other threads:[~2018-04-23 22:41 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-18 14:45 Christopher Lameter
2018-04-18 15:05 ` Mikulas Patocka
2018-04-18 15:11 ` Christopher Lameter
2018-04-18 18:49 ` David Rientjes
2018-04-19 11:00 ` Michal Hocko
2018-04-20 14:53 ` Christopher Lameter
2018-04-21 17:02 ` Vlastimil Babka
2018-04-23 22:41 ` Christopher Lameter [this message]
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