From: Claudiu Manoil <claudiu.manoil@freescale.com>
To: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: David Miller <davem@davemloft.net>, <netdev@vger.kernel.org>,
Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH net-next 2/2] gianfar: convert u64 status counters to atomic64_t
Date: Wed, 13 Feb 2013 17:22:44 +0200 [thread overview]
Message-ID: <511BAFC4.9060006@freescale.com> (raw)
In-Reply-To: <1360715064-2689-3-git-send-email-paul.gortmaker@windriver.com>
On 2/13/2013 2:24 AM, Paul Gortmaker wrote:
> While looking at some asm dump for an unrelated change, Eric
> noticed in the following stats count increment code:
>
> 50b8: 81 3c 01 f8 lwz r9,504(r28)
> 50bc: 81 5c 01 fc lwz r10,508(r28)
> 50c0: 31 4a 00 01 addic r10,r10,1
> 50c4: 7d 29 01 94 addze r9,r9
> 50c8: 91 3c 01 f8 stw r9,504(r28)
> 50cc: 91 5c 01 fc stw r10,508(r28)
>
> that a 64 bit counter was used on ppc-32 without sync
> and hence the "ethtool -S" output was racy.
>
> Here we convert all the values to use atomic64_t so that
> the output will always be consistent.
>
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
Reviewed-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Thanks,
Claudiu
next prev parent reply other threads:[~2013-02-13 15:23 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 [this message]
2013-02-13 16:14 ` Eric Dumazet
2013-02-13 17:47 ` Claudiu Manoil
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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