blosc/blosc2.c: optimize the mutex lock with spin lock

The mutex lock cost lots of cycles in t_blosc_do_job when the thread
number is large. The updating to global values of protected part is
not that heavy. It will save lots of cycles if we Replace the mutex
lock with spin lock.

Apply the patch and test the c-blosc2/bench.
$ ./bench/b2bench blosclz noshuffle single 160 83886080 4

Score gain: 7.4%
CPU: ICX 8380 x 2 sockets
Core number: 160 threads

Author: jiebinn

blosc/blosc2.c

@@ -16,6 +16,7 @@
 #include <sys/types.h>
 #include <assert.h>
 #include <math.h>
+#include <pthread.h>
 
 #include "blosc2.h"
 #include "blosc-private.h"
@@ -3055,10 +3056,10 @@ static void t_blosc_do_job(void *ctxt)
   }
   else {
     // Use dynamic schedule via a queue.  Get the next block.
-    pthread_mutex_lock(&context->count_mutex);
+    pthread_spin_lock(&context->count_spin);
     context->thread_nblock++;
     nblock_ = context->thread_nblock;
-    pthread_mutex_unlock(&context->count_mutex);
+    pthread_spin_unlock(&context->count_spin);
     tblock = nblocks;
   }
 
@@ -3119,15 +3120,15 @@ static void t_blosc_do_job(void *ctxt)
     /* Check results for the compressed/decompressed block */
     if (cbytes < 0) {            /* compr/decompr failure */
       /* Set giveup_code error */
-      pthread_mutex_lock(&context->count_mutex);
+      pthread_spin_lock(&context->count_spin);
       context->thread_giveup_code = cbytes;
-      pthread_mutex_unlock(&context->count_mutex);
+      pthread_spin_unlock(&context->count_spin);
       break;
     }
 
     if (compress && !memcpyed) {
       /* Start critical section */
-      pthread_mutex_lock(&context->count_mutex);
+      pthread_spin_lock(&context->count_spin);
       ntdest = context->output_bytes;
       // Note: do not use a typical local dict_training variable here
       // because it is probably cached from previous calls if the number of
@@ -3138,13 +3139,13 @@ static void t_blosc_do_job(void *ctxt)
 
       if ((cbytes == 0) || (ntdest + cbytes > maxbytes)) {
         context->thread_giveup_code = 0;  /* incompressible buf */
-        pthread_mutex_unlock(&context->count_mutex);
+        pthread_spin_unlock(&context->count_spin);
         break;
       }
       context->thread_nblock++;
       nblock_ = context->thread_nblock;
       context->output_bytes += cbytes;
-      pthread_mutex_unlock(&context->count_mutex);
+      pthread_spin_unlock(&context->count_spin);
       /* End of critical section */
 
       /* Copy the compressed buffer to destination */
@@ -3154,22 +3155,22 @@ static void t_blosc_do_job(void *ctxt)
       nblock_++;
     }
     else {
-      pthread_mutex_lock(&context->count_mutex);
+      pthread_spin_lock(&context->count_spin);
       context->thread_nblock++;
       nblock_ = context->thread_nblock;
       context->output_bytes += cbytes;
-      pthread_mutex_unlock(&context->count_mutex);
+      pthread_spin_unlock(&context->count_spin);
     }
 
   } /* closes while (nblock_) */
 
   if (static_schedule) {
-    pthread_mutex_lock(&context->count_mutex);
+    pthread_spin_lock(&context->count_spin);
     context->output_bytes = context->sourcesize;
     if (compress) {
       context->output_bytes += context->header_overhead;
     }
-    pthread_mutex_unlock(&context->count_mutex);
+    pthread_spin_unlock(&context->count_spin);
   }
 
 }
@@ -3208,7 +3209,7 @@ int init_threadpool(blosc2_context *context) {
   int rc2;
 
   /* Initialize mutex and condition variable objects */
-  pthread_mutex_init(&context->count_mutex, NULL);
+  pthread_spin_init(&context->count_spin, PTHREAD_PROCESS_SHARED);
   pthread_mutex_init(&context->delta_mutex, NULL);
   pthread_mutex_init(&context->nchunk_mutex, NULL);
   pthread_cond_init(&context->delta_cv, NULL);
@@ -3613,7 +3614,7 @@ int release_threadpool(blosc2_context *context) {
     }
 
     /* Release mutex and condition variable objects */
-    pthread_mutex_destroy(&context->count_mutex);
+    pthread_spin_destroy(&context->count_spin);
     pthread_mutex_destroy(&context->delta_mutex);
     pthread_mutex_destroy(&context->nchunk_mutex);
     pthread_cond_destroy(&context->delta_cv);

blosc/context.h

@@ -121,7 +121,7 @@ struct blosc2_context_s {
   int16_t end_threads;
   pthread_t *threads;
   struct thread_context *thread_contexts; /* only for user-managed threads */
-  pthread_mutex_t count_mutex;
+  pthread_spinlock_t count_spin;
   pthread_mutex_t nchunk_mutex;
 #ifdef BLOSC_POSIX_BARRIERS
   pthread_barrier_t barr_init;