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Re: [Qemu-devel] [PATCH V4 10/12] SD card users: optimize access to SDCl

From: Peter Maydell
Subject: Re: [Qemu-devel] [PATCH V4 10/12] SD card users: optimize access to SDClass methods
Date: Tue, 31 Jul 2012 18:47:50 +0100

On 31 July 2012 18:33, Igor Mitsyanko <address@hidden> wrote:
> On 07/31/2012 07:43 PM, Peter Maydell wrote:
>> Anthony claims that SD_GET_CLASS should be cheap enough that we don't
>> need to hoist it out of loops like this. Do you have profiling data
>> or similar that caused you to write this patch?

> Well, I've tested it by measuring an execution time of a 4Kb write to SD
> card, results showed that arithmetic mean of time for one 4k write was less
> by ~300us in sequence with SD_GET_CLASS extracted from the loop.

How much is that as a % of the total time for the write ?

-- PMM

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