On 27 September 2011 14:16, Christian Robottom Reis kiko@linaro.org wrote:
On Tue, Sep 27, 2011 at 09:47:33AM +0100, Ramana Radhakrishnan wrote:
On 26 September 2011 21:51, Michael Hope michael.hope@linaro.org wrote:
Saw this on the linaro-multimedia list: http://lists.linaro.org/pipermail/linaro-multimedia/2011-September/000074.ht...
libpng spends a significant amount of time in memcpy(). This might tie in with Ramana's investigation or the unaligned access work by allowing more memcpy()s to be inlined.
It's the unaligned access and the change / improvements to the memcpy that *might* help in this case. But that ofcourse depends on the compiler knowing when it can do such a thing. Ofcourse what might be more interesting is the kind of workload analysis that Dave's done in the past with memcpy to know what the alignment and size of the buffer being copied is.
If you guys could take a look at this there is a potential requirement for the MMWG around libpng optimization; we could fit this in along with other work (possible vectorizing, etc) on that component.
It wouldn't take long to analyse the memcpy calls - life would be easier if we had the test program and some details on things like what size of images were used in these benchmarks.
Dave