netdev - Re: [net-next PATCH] ixgbe: add counter for times rx pages gets allocated, not recycled

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Message-ID: <1504292993.3922.25.camel@intel.com>
Date:   Fri, 01 Sep 2017 12:09:53 -0700
From:   Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:     Jesper Dangaard Brouer <brouer@...hat.com>, netdev@...r.kernel.org
Cc:     Alexander Duyck <alexander.duyck@...il.com>
Subject: Re: [net-next PATCH] ixgbe: add counter for times rx pages gets
 allocated, not recycled

On Fri, 2017-09-01 at 12:54 +0200, Jesper Dangaard Brouer wrote:
> The ixgbe driver have page recycle scheme based around the RX-ring
> queue, where a RX page is shared between two packets. Based on the
> refcnt, the driver can determine if the RX-page is currently only
> used
> by a single packet, if so it can then directly refill/recycle the
> RX-slot by with the opposite "side" of the page.
> 
> While this is a clever trick, it is hard to determine when this
> recycling is successful and when it fails.  Adding a counter, which
> is
> available via ethtool --statistics as 'alloc_rx_page'.  Which counts
> the number of times the recycle fails and the real page allocator is
> invoked.  When interpreting the stats, do remember that every alloc
> will serve two packets.
> 
> The counter is collected per rx_ring, but is summed and ethtool
> exported as 'alloc_rx_page'.  It would be relevant to know what
> rx_ring that cannot keep up, but that can be exported later if
> someone experience a need for this.
> 
> Signed-off-by: Jesper Dangaard Brouer <brouer@...hat.com>

Since Alex has a suggested change for this patch, when you resubmit v2,
can you make sure you CC intel-wired-lan mailing list, so that my
patchwork project picks up this patch?  Thanks in advance Jesper.
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