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

[Igor Mitsyanko]

On 07/31/2012 09:47 PM, Peter Maydell wrote:
> 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
total write time was ~3.5-4.0 ms I think, so its ~0.08%