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gallium/util: start with a random L3 cache index for AMD Zen

This commit is contained in:
Marek Olšák 2018-09-07 15:37:45 -04:00
parent 936e0dcd61
commit 7d41a7593a
1 changed files with 16 additions and 4 deletions
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20
src/gallium/auxiliary/util/u_helpers.c
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@ -30,6 +30,7 @@
#include "util/u_inlines.h"
#include "util/u_upload_mgr.h"
#include "util/u_thread.h"
#include "util/os_time.h"
#include <inttypes.h>
/**
@ -120,6 +121,17 @@ util_upload_index_buffer(struct pipe_context *pipe,
return *out_buffer != NULL;
}
static unsigned L3_cache_number;
static once_flag init_cache_number_flag = ONCE_FLAG_INIT;
static void
util_init_cache_number(void)
{
/* Get a semi-random number. */
int64_t t = os_time_get_nano();
L3_cache_number = (t ^ (t >> 8) ^ (t >> 16));
}
/**
* Called by MakeCurrent. Used to notify the driver that the application
* thread may have been changed.
@ -141,12 +153,12 @@ util_context_thread_changed(struct pipe_context *ctx, thrd_t *upper_thread)
/* If the main thread is not pinned, choose the L3 cache. */
if (cache == -1) {
unsigned num_caches = util_cpu_caps.nr_cpus /
util_cpu_caps.cores_per_L3;
static unsigned last_cache;
unsigned num_L3_caches = util_cpu_caps.nr_cpus /
util_cpu_caps.cores_per_L3;
/* Choose a different L3 cache for each subsequent MakeCurrent. */
cache = p_atomic_inc_return(&last_cache) % num_caches;
call_once(&init_cache_number_flag, util_init_cache_number);
cache = p_atomic_inc_return(&L3_cache_number) % num_L3_caches;
util_pin_thread_to_L3(current, cache, util_cpu_caps.cores_per_L3);
}