Message-ID: <1481137249.4930.59.camel@edumazet-glaptop3.roam.corp.google.com>
Subject: Re: [PATCH] mm: page_alloc: High-order per-cpu page allocator v7
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Christoph Lameter <cl@linux.com>, Michal Hocko <mhocko@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>, Johannes Weiner <hannes@cmpxchg.org>,
        Jesper Dangaard Brouer <brouer@redhat.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>, Linux-MM <linux-mm@kvack.org>,
        Linux-Kernel <linux-kernel@vger.kernel.org>
Date: Wed, 07 Dec 2016 11:00:49 -0800
In-Reply-To: <20161207101228.8128-1-mgorman@techsingularity.net>
References: <20161207101228.8128-1-mgorman@techsingularity.net>
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On Wed, 2016-12-07 at 10:12 +0000, Mel Gorman wrote:

> This is the result from netperf running UDP_STREAM on localhost. It was
> selected on the basis that it is slab-intensive and has been the subject
> of previous SLAB vs SLUB comparisons with the caveat that this is not
> testing between two physical hosts.
> 

Interesting results.

netperf UDP_STREAM is not really slab intensive : (for large sendsizes
like 16KB)

Bulk of the storage should be allocated from alloc_skb_with_frags(),
ie using pages.

And I am not sure we enabled high order pages in this path ?

ip_make_skb()
 __ip_append_data()
  sock_alloc_send_skb()
   sock_alloc_send_pskb (...,  max_page_order=0)
    alloc_skb_with_frags ( max_page_order=0)
 
So far, I believe net/unix/af_unix.c uses PAGE_ALLOC_COSTLY_ORDER as
max_order, but UDP does not do that yet.

We probably could enable high-order pages there, if we believe this is
okay.

Or maybe I missed and this already happened ? ;)

Thanks.