[Mesa-dev] [PATCH 1/2] st/mesa: regularly re-pin driver threads to the CCX where the app thread is

[Dave Airlie]

Seems to be a more reasonable solution than previously,

Reviewed-by: Dave Airlie <airlied at redhat.com>
On Wed, 21 Nov 2018 at 09:50, Marek Olšák <maraeo at gmail.com> wrote:
>
> Ping
>
> On Mon, Nov 12, 2018 at 7:21 PM Marek Olšák <maraeo at gmail.com> wrote:
>>
>> From: Marek Olšák <marek.olsak at amd.com>
>>
>> This is used when glthread is disabled.
>>
>> Mesa pretty much chases the app thread on the CPU.
>> The performance is the same as pinning the app thread.
>> ---
>>  src/mesa/state_tracker/st_context.h |  2 ++
>>  src/mesa/state_tracker/st_draw.c    | 32 +++++++++++++++++++++++++++++
>>  2 files changed, 34 insertions(+)
>>
>> diff --git a/src/mesa/state_tracker/st_context.h b/src/mesa/state_tracker/st_context.h
>> index 14b9b018809..95133c7020f 100644
>> --- a/src/mesa/state_tracker/st_context.h
>> +++ b/src/mesa/state_tracker/st_context.h
>> @@ -186,20 +186,22 @@ struct st_context
>>        uint8_t sample_locations[
>>           PIPE_MAX_SAMPLE_LOCATION_GRID_SIZE *
>>           PIPE_MAX_SAMPLE_LOCATION_GRID_SIZE * 32];
>>     } state;
>>
>>     uint64_t dirty; /**< dirty states */
>>
>>     /** This masks out unused shader resources. Only valid in draw calls. */
>>     uint64_t active_states;
>>
>> +   unsigned pin_thread_counter; /* for L3 thread pinning on AMD Zen */
>> +
>>     /* If true, further analysis of states is required to know if something
>>      * has changed. Used mainly for shaders.
>>      */
>>     bool gfx_shaders_may_be_dirty;
>>     bool compute_shader_may_be_dirty;
>>
>>     GLboolean vertdata_edgeflags;
>>     GLboolean edgeflag_culls_prims;
>>
>>     struct st_vertex_program *vp;    /**< Currently bound vertex program */
>> diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
>> index eb52d9505b6..5910ffa5bda 100644
>> --- a/src/mesa/state_tracker/st_draw.c
>> +++ b/src/mesa/state_tracker/st_draw.c
>> @@ -51,28 +51,36 @@
>>  #include "st_atom.h"
>>  #include "st_cb_bitmap.h"
>>  #include "st_cb_bufferobjects.h"
>>  #include "st_cb_xformfb.h"
>>  #include "st_debug.h"
>>  #include "st_draw.h"
>>  #include "st_program.h"
>>
>>  #include "pipe/p_context.h"
>>  #include "pipe/p_defines.h"
>> +#include "util/u_cpu_detect.h"
>>  #include "util/u_inlines.h"
>>  #include "util/u_format.h"
>>  #include "util/u_prim.h"
>>  #include "util/u_draw.h"
>>  #include "util/u_upload_mgr.h"
>>  #include "draw/draw_context.h"
>>  #include "cso_cache/cso_context.h"
>>
>> +#ifdef PIPE_OS_LINUX
>> +#include <sched.h>
>> +#define HAVE_SCHED_GETCPU 1
>> +#else
>> +#define sched_getcpu() 0
>> +#define HAVE_SCHED_GETCPU 0
>> +#endif
>>
>>  /**
>>   * Set the restart index.
>>   */
>>  static void
>>  setup_primitive_restart(struct gl_context *ctx, struct pipe_draw_info *info)
>>  {
>>     if (ctx->Array._PrimitiveRestart) {
>>        unsigned index_size = info->index_size;
>>
>> @@ -115,20 +123,44 @@ prepare_draw(struct st_context *st, struct gl_context *ctx)
>>     if (unlikely(!st->bitmap.cache.empty))
>>        st_flush_bitmap_cache(st);
>>
>>     st_invalidate_readpix_cache(st);
>>
>>     /* Validate state. */
>>     if ((st->dirty | ctx->NewDriverState) & ST_PIPELINE_RENDER_STATE_MASK ||
>>         st->gfx_shaders_may_be_dirty) {
>>        st_validate_state(st, ST_PIPELINE_RENDER);
>>     }
>> +
>> +   struct pipe_context *pipe = st->pipe;
>> +
>> +   /* Pin threads regularly to the same Zen CCX that the main thread is
>> +    * running on. The main thread can move between CCXs.
>> +    */
>> +   if (unlikely(HAVE_SCHED_GETCPU && /* Linux */
>> +                /* AMD Zen */
>> +                util_cpu_caps.nr_cpus != util_cpu_caps.cores_per_L3 &&
>> +                /* no glthread */
>> +                ctx->CurrentClientDispatch != ctx->MarshalExec &&
>> +                /* driver support */
>> +                pipe->set_context_param &&
>> +                /* do it occasionally */
>> +                ++st->pin_thread_counter % 512 == 0)) {
>> +      int cpu = sched_getcpu();
>> +      if (cpu >= 0) {
>> +         unsigned L3_cache = cpu / util_cpu_caps.cores_per_L3;
>> +
>> +         pipe->set_context_param(pipe,
>> +                                 PIPE_CONTEXT_PARAM_PIN_THREADS_TO_L3_CACHE,
>> +                                 L3_cache);
>> +      }
>> +   }
>>  }
>>
>>  /**
>>   * This function gets plugged into the VBO module and is called when
>>   * we have something to render.
>>   * Basically, translate the information into the format expected by gallium.
>>   */
>>  static void
>>  st_draw_vbo(struct gl_context *ctx,
>>              const struct _mesa_prim *prims,
>> --
>> 2.17.1
>>
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