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Re: [Qemu-devel] [PATCH V4 10/12] SD card users: optimize access to SDCl
Re: [Qemu-devel] [PATCH V4 10/12] SD card users: optimize access to SDClass methods
Tue, 31 Jul 2012 21:33:04 +0400
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On 07/31/2012 07:43 PM, Peter Maydell wrote:
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.
Although I ran this test several times, I have little faith in test
methodology and results, it obviously showed significant dispersion
between measured time of distinct 4K writes (200-300% if I recall
correctly). I really have no objection no objection to dropping this patch.
On 27 July 2012 20:29, Igor Mitsyanko <address@hidden> wrote:
Rather that repeatedly call SD_GET_CLASS() in a loop, call it once before
a loop starts.
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?
[Qemu-devel] [PATCH V4 08/12] hw/sd.c: add SD card save/load support, Igor Mitsyanko, 2012/07/27
[Qemu-devel] [PATCH V4 10/12] SD card users: optimize access to SDClass methods, Igor Mitsyanko, 2012/07/27
[Qemu-devel] [PATCH V4 07/12] hw/sd.c: make sd_wp_addr() return bool, Igor Mitsyanko, 2012/07/27
[Qemu-devel] [PATCH V4 12/12] hw/sd.c: introduce SD card "drive" property, Igor Mitsyanko, 2012/07/27
- Re: [Qemu-devel] [PATCH V4 11/12] SD card: introduce "spi" property for SD card objects, (continued)