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From: Eric Dumazet <edumazet@google.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: __GFP_REPEAT usage in fq_alloc_node
Date: Mon, 9 Jan 2017 08:00:16 -0800	[thread overview]
Message-ID: <CANn89iKcHqyr=af2R7WyZRPawXt_bZkFAsbk0W_tkVt9VOGYFQ@mail.gmail.com> (raw)
In-Reply-To: <20170109102219.GF7495@dhcp22.suse.cz>

On Mon, Jan 9, 2017 at 2:22 AM, Michal Hocko <mhocko@kernel.org> wrote:
>
> the changelog doesn't mention it but this, unlike other kvmalloc
> conversions is not without functional changes. The kmalloc part
> will be weaker than it is with the original code for !costly (<64kB)
> requests, because we are enforcing __GFP_NORETRY to break out from the
> page allocator which doesn't really fail such a small requests.
>
> Now the question is what those code paths really prefer. Do they really
> want to potentially loop in the page allocator and invoke the OOM killer
> when the memory is short/fragmeted? I mean we can get into a situation
> when no order-3 pages can be compacted and shooting the system down just
> for that reason sounds quite dangerous to me.
>
> So the main question is how hard should we try before falling back to
> vmalloc here?

This patch is fine :

1) Default hash size is 1024 slots, 8192 bytes on 64bit arches.
2) Most of the times, qdisc are setup at boot time.

  reply	other threads:[~2017-01-09 16:00 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-06 15:20 __GFP_REPEAT usage in fq_alloc_node Michal Hocko
2017-01-06 15:39 ` Eric Dumazet
2017-01-06 16:07   ` Michal Hocko
2017-01-06 16:19     ` Michal Hocko
2017-01-07  3:33       ` [PATCH] net: use kvmalloc rather than open coded variant kbuild test robot
2017-01-07  9:19         ` Michal Hocko
2017-01-07  3:35       ` kbuild test robot
2017-01-09 10:22       ` __GFP_REPEAT usage in fq_alloc_node Michal Hocko
2017-01-09 16:00         ` Eric Dumazet [this message]
2017-01-09 17:45           ` Michal Hocko
2017-01-09 17:53             ` Eric Dumazet
2017-01-14 23:43     ` [PATCH] net_sched: use kvmalloc rather than opencoded variant kbuild test robot
2017-01-16  8:54       ` Michal Hocko
2017-01-06 16:31   ` __GFP_REPEAT usage in fq_alloc_node Vlastimil Babka
2017-01-06 16:48     ` Eric Dumazet
2017-01-06 16:50       ` Eric Dumazet
2017-01-06 16:55       ` Vlastimil Babka
2017-01-06 17:08         ` Eric Dumazet
2017-01-06 17:18           ` Vlastimil Babka

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