[vlc-devel] [PATCH] [RFC] video_chroma: copy: use an 8KB cache line instead of 4KB

[Rémi Denis-Courmont]

On May 10, 2017 12:13:49 PM GMT+03:00, Steve Lhomme <robux4 at videolabs.io> wrote:
>Without this it's impossible to do some processing like splitting NV12
>UV
>planes, it requires double the resolution. In that case the code
>asserts on
>assert(hstep > 0) in SSE_SplitPlanes().
>
>--
>this is an RFC as their might be side effects in using more memory by
>default
>or a larger memory page.
>---
> modules/video_chroma/copy.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/modules/video_chroma/copy.c b/modules/video_chroma/copy.c
>index 444d47a7a7..98816d4686 100644
>--- a/modules/video_chroma/copy.c
>+++ b/modules/video_chroma/copy.c
>@@ -35,7 +35,7 @@
> int CopyInitCache(copy_cache_t *cache, unsigned width)
> {
> #ifdef CAN_COMPILE_SSE2
>-    cache->size = __MAX((width + 0x3f) & ~ 0x3f, 4096);
>+    cache->size = __MAX((width + 0x3f) & ~ 0x3f, 8192);
>     cache->buffer = vlc_memalign(64, cache->size);
>     if (!cache->buffer)
>         return VLC_EGENERIC;
>-- 
>2.12.1
>
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Hello,

Aligning on more than page size wouldn't make much sense (except for non-portable huge pages). Allocating more than a page size should be fine.

Not that I know the code in question that well.
-- 
Rémi Denis-Courmont