netdev - Re: [net-next PATCH 0/6] Add skb_free_frag to replace put_page(virt_to_head

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Date:	Tue, 05 May 2015 19:28:51 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	alexander.h.duyck@...hat.com
Cc:	linux-mm@...ck.org, netdev@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [net-next PATCH 0/6] Add skb_free_frag to replace
 put_page(virt_to_head_page(ptr))

From: Alexander Duyck <alexander.h.duyck@...hat.com>
Date: Mon, 04 May 2015 16:14:42 -0700

> This patch set cleans up some of the handling of page frags used in the skb
> allocation.  The issue was we were having to use a number of calls to
> virt_to_head_page in a number of places and then following that up with
> put_page.  Both calls end up being expensive, the first due to size, and
> the second due to the fact that we end up having to call a number of other
> functions before we finally see the page freed in the case of compound
> pages.
> 
> The skb_free_frag function is meant to resolve that by providing a
> centralized location for the virt_to_head_page call and by coalesing
> several checks such as the check for PageHead into a single check so that
> we can keep the instruction cound minimal when freeing the page frag.
> 
> With this change I am seeing an improvement of about 5% in a simple
> receive/drop test.

I'm going to need to see some buyin from the mm folks on this series.
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