From: Claudiu Manoil <claudiu.manoil@freescale.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>,
David Miller <davem@davemloft.net>, <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next 2/2] gianfar: convert u64 status counters to atomic64_t
Date: Wed, 13 Feb 2013 19:47:20 +0200 [thread overview]
Message-ID: <511BD1A8.4090506@freescale.com> (raw)
In-Reply-To: <1360772065.6884.23.camel@edumazet-glaptop>
On 2/13/2013 6:14 PM, Eric Dumazet wrote:
> On Wed, 2013-02-13 at 17:22 +0200, Claudiu Manoil wrote:
>
>> At least it seems that this conversion results in fewer asm
>> instructions, as apparently addze and the double lwz/stw are
>> not generated anymore. Hopefully it's faster too :P
>
> Strange, could you show us these asm instructions ?
>
>
>
Ok, I'm looking over gfar_clean_rx_ring's asm code, with and w/o this
patch. They are difficult to compare as asm code changed considerably,
the initial version having more lines.
The first thing I notice is that the initial ver has 13 'addic'
instructions, and the new version has 7.
Now taking the code around the last 'addic' instruction (from the
gfar_clean_rx_ring function):
Initial version looks like this:
5024: 4b ff ff ac b 4fd0 <gfar_clean_rx_ring+0x450>
5028: 81 5d 06 30 lwz r10,1584(r29)
502c: 81 7d 06 34 lwz r11,1588(r29)
5030: 31 6b 00 01 addic r11,r11,1
5034: 7d 4a 01 94 addze r10,r10
5038: 91 5d 06 30 stw r10,1584(r29)
503c: 91 7d 06 34 stw r11,1588(r29)
5040: 4b ff fe fc b 4f3c <gfar_clean_rx_ring+0x3bc>
New version looks like this:
4ff8: 4b ff fd a8 b 4da0 <gfar_clean_rx_ring+0x1ec>
4ffc: 80 1c 00 a0 lwz r0,160(r28)
5000: 38 60 00 00 li r3,0
5004: 80 a1 00 18 lwz r5,24(r1)
5008: 38 80 00 01 li r4,1
500c: 30 00 00 01 addic r0,r0,1
5010: 90 1c 00 a0 stw r0,160(r28)
5014: 48 00 00 01 bl 5014 <gfar_clean_rx_ring+0x460>
5018: 4b ff ff 4c b 4f64 <gfar_clean_rx_ring+0x3b0>
I have the whole function's asm excepts, if needed.
next prev parent reply other threads:[~2013-02-13 17:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 0:24 [PATCH net-next 0/2] gianfar: make local stats atomic64 Paul Gortmaker
2013-02-13 0:24 ` [PATCH net-next 1/2] gianfar: remove largely unused gfar_stats struct Paul Gortmaker
2013-02-13 13:13 ` Claudiu Manoil
2013-02-13 0:24 ` [PATCH net-next 2/2] gianfar: convert u64 status counters to atomic64_t Paul Gortmaker
2013-02-13 15:22 ` Claudiu Manoil
2013-02-13 16:14 ` Eric Dumazet
2013-02-13 17:47 ` Claudiu Manoil [this message]
2013-02-13 18:03 ` Eric Dumazet
2013-02-13 18:18 ` [PATCH net-next 0/2] gianfar: make local stats atomic64 David Miller
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