[Mesa-dev] [Bug 107670] Massive slowdown under specific memcpy implementations (32bit, no-SIMD, backward copy).

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=107670

--- Comment #2 from iive at yahoo.com ---
(In reply to Timothy Arceri from comment #1)
> There already is asm optimized version of memcpy() in glibc. Why would we
> want to reinvent that in Mesa?
> 
> glibc should pick the right implementation for you system.

Because some implementations copy data backwards and this creates a huge
problem when it is written over PCIe.

To be clear:
for(i=0;i<size;i++)    dst[i]=src[i]; // forward copy.
for(i=size-1;i>=0;i--) dst[i]=src[i]; // backwards copy

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/mesa-dev/attachments/20180824/95a286b0/attachment.html>