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Subject: Re: [PATCH v2] fs/select: add vmalloc fallback for select(2)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
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        linux-mm@kvack.org, Michal Hocko <mhocko@kernel.org>,
        netdev@vger.kernel.org
Date: Mon, 26 Sep 2016 18:38:44 -0700
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On Mon, 2016-09-26 at 17:01 -0700, Andrew Morton wrote:

> I don't share Eric's concerns about performance here.  If the vmalloc()
> is called, we're about to write to that quite large amount of memory
> which we just allocated, and the vmalloc() overhead will be relatively
> low.

I did not care of the performance of this particular select() system
call really, but other cpus because of more TLB invalidations.

At least CONFIG_DEBUG_PAGEALLOC=y builds should be impacted, but maybe
we do not care.