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tests/vgem_fb_test: Remove volatile

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By simply removing volatile qualifier in draw() from uint32_t *ptr, memory
accesses improve a lot in that test. We practically saw 1 order of magnitude in
the performance of VGEM and the speed was equally on using drm_intel specific
ioctls.

The inclusion of volatile has forced the compiler to load and store the
variable from memory on every run, hurting quite badly the performance.
Therefore, performance is dropped due many read operations in the mapped
pointer which is a no-no when objects are write-combining mapped.

This patch also removes sleep, that bothers performance measurements
This commit is contained in:
Tiago Vignatti 2015-07-02 18:24:04 -03:00
parent 1319c565ec
commit 1f937389fc
1 changed files with 1 additions and 4 deletions
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5
tests/vgem_fb_test.c
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@ -259,7 +259,7 @@ static void draw(struct context *ctx) {
size_t bo_stride = gbm_bo_get_stride(ctx->gbm_buffer[fb_idx]);
size_t bo_size = gbm_bo_get_stride(ctx->gbm_buffer[fb_idx]) * gbm_bo_get_height(ctx->gbm_buffer[fb_idx]);
uint32_t *bo_ptr;
volatile uint32_t *ptr;
uint32_t *ptr;
struct timeval start, end;
for (sequence_subindex = 0; sequence_subindex < 4; sequence_subindex++) {
@ -306,11 +306,8 @@ static void draw(struct context *ctx) {
break;
}
}
munmap(bo_ptr, bo_size);
usleep(1e6 / 120); /* 120 Hz */
fb_idx = fb_idx ^ 1;
}
}