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From: Michal Hocko <mhocko@kernel.org>
To: Shakeel Butt <shakeelb@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>,
	Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 7/9] net: use kvmalloc with __GFP_REPEAT rather than open coded variant
Date: Fri, 31 Mar 2017 10:46:53 +0200
Message-ID: <20170331084652.GL27098@dhcp22.suse.cz> (raw)
In-Reply-To: <CALvZod73-ddnbMAWXF9QpXMcpjZMLreLXheUo-CgcB7s_5iBnQ@mail.gmail.com>

On Thu 30-03-17 16:21:43, Shakeel Butt wrote:
> On Mon, Mar 6, 2017 at 2:33 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > From: Michal Hocko <mhocko@suse.com>
> >
> > fq_alloc_node, alloc_netdev_mqs and netif_alloc* open code kmalloc
> > with vmalloc fallback. Use the kvmalloc variant instead. Keep the
> > __GFP_REPEAT flag based on explanation from Eric:
> > "
> > At the time, tests on the hardware I had in my labs showed that
> > vmalloc() could deliver pages spread all over the memory and that was a
> > small penalty (once memory is fragmented enough, not at boot time)
> > "
> >
> > The way how the code is constructed means, however, that we prefer to go
> > and hit the OOM killer before we fall back to the vmalloc for requests
> > <=32kB (with 4kB pages) in the current code. This is rather disruptive for
> > something that can be achived with the fallback. On the other hand
> > __GFP_REPEAT doesn't have any useful semantic for these requests. So the
> > effect of this patch is that requests smaller than 64kB will fallback to
> 
> I am a bit confused about this 64kB, shouldn't it be <=32kB (with 4kB
> pages & PAGE_ALLOC_COSTLY_ORDER = 3)?

You are right. I just forgot to update wording. "mm: support
__GFP_REPEAT in kvmalloc_node for >32kB" was fixed but this one stayed
in place.

s@smaller than 64kB@which fit into 32kB@

Andrew could you update the changelog please?
-- 
Michal Hocko
SUSE Labs

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Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-06 10:30 [PATCH 0/6 v5] kvmalloc Michal Hocko
2017-03-06 10:30 ` [PATCH 1/9] mm: introduce kv[mz]alloc helpers Michal Hocko
2017-06-02  7:17   ` Levin, Alexander (Sasha Levin)
2017-06-02  7:28     ` Michal Hocko
2017-06-02  7:40       ` Levin, Alexander (Sasha Levin)
2017-06-02  7:50         ` Michal Hocko
2017-03-06 10:30 ` [PATCH 2/9] mm: support __GFP_REPEAT in kvmalloc_node for >32kB Michal Hocko
2017-04-07  0:45   ` Shakeel Butt
2017-04-07  7:40     ` Michal Hocko
2017-03-06 10:30 ` [PATCH 3/9] rhashtable: simplify a strange allocation pattern Michal Hocko
2017-03-06 10:30 ` [PATCH 4/9] ila: " Michal Hocko
2017-03-06 10:33 ` [PATCH 5/9] xattr: zero out memory copied to userspace in getxattr Michal Hocko
2017-03-06 10:33   ` [PATCH 6/9] treewide: use kv[mz]alloc* rather than opencoded variants Michal Hocko
2017-03-06 10:33   ` [PATCH 7/9] net: use kvmalloc with __GFP_REPEAT rather than open coded variant Michal Hocko
2017-03-30 23:21     ` Shakeel Butt
2017-03-31  8:46       ` Michal Hocko [this message]
2017-03-06 10:33   ` [PATCH 8/9] md: use kvmalloc rather than opencoded variant Michal Hocko
2017-03-06 10:33   ` [PATCH 9/9] bcache: use kvmalloc Michal Hocko

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