From: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
To: Tom Herbert <therbert@google.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: Re: [PATCH 1/4] e1000e: save skb counts in TX to avoid cache misses
Date: Mon, 26 Apr 2010 15:01:49 -0700 [thread overview]
Message-ID: <n2p9929d2391004261501va61b955xaef62e9604a8e34d@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.1.00.1004231719050.16806@pokey.mtv.corp.google.com>
On Fri, Apr 23, 2010 at 17:25, Tom Herbert <therbert@google.com> wrote:
> In e1000_tx_map, precompute number of segements and bytecounts which
> are derived from fields in skb; these are stored in buffer_info. When
> cleaning tx in e1000_clean_tx_irq use the values in the associated
> buffer_info for statistics counting, this eliminates cache misses
> on skb fields.
>
> Signed-off-by: Tom Herbert <therbert@google.com>
> ---
> diff --git a/drivers/net/e1000e/e1000.h b/drivers/net/e1000e/e1000.h
> index 12648a1..d6da75b 100644
> --- a/drivers/net/e1000e/e1000.h
> +++ b/drivers/net/e1000e/e1000.h
> @@ -188,6 +188,8 @@ struct e1000_buffer {
> unsigned long time_stamp;
> u16 length;
> u16 next_to_watch;
> + unsigned int segs;
> + unsigned int bytecount;
> u16 mapped_as_page;
> };
> /* Rx */
> diff --git a/drivers/net/e1000e/netdev.c b/drivers/net/e1000e/netdev.c
> index 5f70c43..4f5034a 100644
> --- a/drivers/net/e1000e/netdev.c
> +++ b/drivers/net/e1000e/netdev.c
> @@ -646,14 +635,8 @@ static bool e1000_clean_tx_irq(struct e1000_adapter *adapter)
> cleaned = (i == eop);
>
> if (cleaned) {
> - struct sk_buff *skb = buffer_info->skb;
> - unsigned int segs, bytecount;
> - segs = skb_shinfo(skb)->gso_segs ?: 1;
> - /* multiply data chunks by size of headers */
> - bytecount = ((segs - 1) * skb_headlen(skb)) +
> - skb->len;
> - total_tx_packets += segs;
> - total_tx_bytes += bytecount;
> + total_tx_packets += buffer_info->segs;
> + total_tx_bytes += buffer_info->bytecount;
> }
>
> e1000_put_txbuf(adapter, buffer_info);
> @@ -3906,7 +3889,7 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
> struct e1000_buffer *buffer_info;
> unsigned int len = skb_headlen(skb);
> unsigned int offset = 0, size, count = 0, i;
> - unsigned int f;
> + unsigned int f, bytecount, segs;
>
> i = tx_ring->next_to_use;
>
> @@ -3965,7 +3948,13 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
> }
> }
>
> + segs = skb_shinfo(skb)->gso_segs ?: 1;
> + /* multiply data chunks by size of headers */
> + bytecount = ((segs - 1) * skb_headlen(skb)) + skb->len;
> +
> tx_ring->buffer_info[i].skb = skb;
> + tx_ring->buffer_info[i].segs = segs;
> + tx_ring->buffer_info[i].bytecount = bytecount;
> tx_ring->buffer_info[first].next_to_watch = i;
>
> return count;
> --
>
I have added your patches to my queue of e1000e patches, thanks.
--
Cheers,
Jeff
prev parent reply other threads:[~2010-04-26 22:01 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-24 0:25 [PATCH 1/4] e1000e: save skb counts in TX to avoid cache misses Tom Herbert
2010-04-24 6:30 ` David Miller
2010-04-26 15:55 ` Alexander Duyck
2010-04-26 22:01 ` Jeff Kirsher [this message]
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