linux-kernel - Re: __GFP_REPEAT usage in fq_alloc

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Message-ID: <CANn89i+QZs0cSPK21qMe6LXw+AeAMZ_tKEDUEnCsJ_cd+q0t-g@mail.gmail.com>
Date:   Fri, 6 Jan 2017 07:39:14 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: __GFP_REPEAT usage in fq_alloc_node

On Fri, Jan 6, 2017 at 7:20 AM, Michal Hocko <mhocko@...nel.org> wrote:
>
> Hi Eric,
> I am currently checking kmalloc with vmalloc fallback users and convert
> them to a new kvmalloc helper [1]. While I am adding a support for
> __GFP_REPEAT to kvmalloc [2] I was wondering what is the reason to use
> __GFP_REPEAT in fq_alloc_node in the first place. c3bd85495aef
> ("pkt_sched: fq: more robust memory allocation") doesn't mention
> anything. Could you clarify this please?
>
> Thanks!

I guess this question applies to all __GFP_REPEAT usages in net/ ?

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)

I guess this wont be anymore a concern if I can finish my pending work
about vmalloc() trying to get adjacent pages
https://lkml.org/lkml/2016/12/21/285

Thanks.