From: Yegor Yefremov <yegorslists@googlemail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev <netdev@vger.kernel.org>, davem@davemloft.net
Subject: Re: [PATCH 1/1] KS8695: update ksp->next_rx_desc_read at the end of rx loop
Date: Wed, 17 Mar 2010 10:39:30 +0100 [thread overview]
Message-ID: <f69abfc31003170239k2d64aa8bgbe3f3ae59a074a05@mail.gmail.com> (raw)
In-Reply-To: <1268754720.3094.55.camel@edumazet-laptop>
On Tue, Mar 16, 2010 at 4:52 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> Le mardi 16 mars 2010 à 16:42 +0100, Yegor Yefremov a écrit :
>> KS8695: update ksp->next_rx_desc_read at the end of rx loop
>>
>> There is no need to adjust the next rx descriptor after each packet,
>> so do it only once at the end of the routine.
>>
>> Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
>>
>> Index: linux-2.6.34-rc1/drivers/net/arm/ks8695net.c
>> ===================================================================
>> --- linux-2.6.34-rc1.orig/drivers/net/arm/ks8695net.c
>> +++ linux-2.6.34-rc1/drivers/net/arm/ks8695net.c
>> @@ -538,12 +538,13 @@ rx_finished:
>> */
>> last_rx_processed = buff_n;
>> buff_n = (buff_n + 1) & MAX_RX_DESC_MASK;
>> - /*And note which RX descriptor we last did */
>> - if (likely(last_rx_processed != -1))
>> - ksp->next_rx_desc_read =
>> - (last_rx_processed + 1) &
>> - MAX_RX_DESC_MASK;
>> }
>> +
>> + /*And note which RX descriptor we last did */
>> + if (likely(last_rx_processed != -1))
>> + ksp->next_rx_desc_read =
>> + (last_rx_processed + 1) & MAX_RX_DESC_MASK;
>> +
>
> Very strange to see all these computations...
>
> At this point, why not use
>
> if (likely(last_rx_processed != -1))
> ksp->next_rx_desc_read = buff_n;
>
> or even get rid of last_rx_processed completely and do :
>
>
> diff --git a/drivers/net/arm/ks8695net.c b/drivers/net/arm/ks8695net.c
> index a1d4188..ac6ab04 100644
> --- a/drivers/net/arm/ks8695net.c
> +++ b/drivers/net/arm/ks8695net.c
> @@ -461,7 +461,6 @@ static int ks8695_rx(struct ks8695_priv *ksp, int budget)
> int buff_n;
> u32 flags;
> int pktlen;
> - int last_rx_processed = -1;
> int received = 0;
>
> buff_n = ksp->next_rx_desc_read;
> @@ -533,17 +532,9 @@ rx_failure:
> ksp->rx_ring[buff_n].status = cpu_to_le32(RDES_OWN);
> rx_finished:
> received++;
> - /* And note this as processed so we can start
> - * from here next time
> - */
> - last_rx_processed = buff_n;
> buff_n = (buff_n + 1) & MAX_RX_DESC_MASK;
> - /*And note which RX descriptor we last did */
> - if (likely(last_rx_processed != -1))
> - ksp->next_rx_desc_read =
> - (last_rx_processed + 1) &
> - MAX_RX_DESC_MASK;
> }
> + ksp->next_rx_desc_read = buff_n;
> /* And refill the buffers */
> ks8695_refill_rxbuffers(ksp);
Thank you for reviewing. Great idea. This simplifies the driver a
little. I tested your patch and everything is working as before. I
also added your signed-off-by and made some beatifications.
Yegor
next prev parent reply other threads:[~2010-03-17 9:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-16 15:42 [PATCH 1/1] KS8695: update ksp->next_rx_desc_read at the end of rx loop Yegor Yefremov
2010-03-16 15:52 ` Eric Dumazet
2010-03-17 9:39 ` Yegor Yefremov [this message]
2010-03-17 9:40 ` Yegor Yefremov
2010-03-20 5:44 ` David Miller
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