Date: Wed, 14 Feb 2018 00:31:37 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r329253 - stable/11/usr.bin/sort Message-ID: <201802140031.w1E0VbCg009299@repo.freebsd.org>
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Author: markj Date: Wed Feb 14 00:31:37 2018 New Revision: 329253 URL: https://svnweb.freebsd.org/changeset/base/329253 Log: MFC r312667 (by pfg): sort - Don't live-loop threads. Modified: stable/11/usr.bin/sort/radixsort.c Directory Properties: stable/11/ (props changed) Modified: stable/11/usr.bin/sort/radixsort.c ============================================================================== --- stable/11/usr.bin/sort/radixsort.c Wed Feb 14 00:25:18 2018 (r329252) +++ stable/11/usr.bin/sort/radixsort.c Wed Feb 14 00:31:37 2018 (r329253) @@ -83,12 +83,12 @@ static struct level_stack *g_ls; #if defined(SORT_THREADS) /* stack guarding mutex */ +static pthread_cond_t g_ls_cond; static pthread_mutex_t g_ls_mutex; /* counter: how many items are left */ static size_t sort_left; /* guarding mutex */ -static pthread_mutex_t sort_left_mutex; /* semaphore to count threads */ static sem_t mtsem; @@ -99,23 +99,25 @@ static sem_t mtsem; static inline void sort_left_dec(size_t n) { - - pthread_mutex_lock(&sort_left_mutex); + pthread_mutex_lock(&g_ls_mutex); sort_left -= n; - pthread_mutex_unlock(&sort_left_mutex); + if (sort_left == 0 && nthreads > 1) + pthread_cond_broadcast(&g_ls_cond); + pthread_mutex_unlock(&g_ls_mutex); } /* * Do we have something to sort ? + * + * This routine does not need to be locked. */ static inline bool have_sort_left(void) { bool ret; - pthread_mutex_lock(&sort_left_mutex); ret = (sort_left > 0); - pthread_mutex_unlock(&sort_left_mutex); + return (ret); } @@ -146,6 +148,11 @@ push_ls(struct sort_level *sl) #if defined(SORT_THREADS) if (nthreads > 1) + pthread_cond_signal(&g_ls_cond); +#endif + +#if defined(SORT_THREADS) + if (nthreads > 1) pthread_mutex_unlock(&g_ls_mutex); #endif } @@ -184,13 +191,19 @@ pop_ls_mt(void) pthread_mutex_lock(&g_ls_mutex); - if (g_ls) { - sl = g_ls->sl; - saved_ls = g_ls; - g_ls = g_ls->next; - } else { + for (;;) { + if (g_ls) { + sl = g_ls->sl; + saved_ls = g_ls; + g_ls = g_ls->next; + break; + } sl = NULL; saved_ls = NULL; + + if (have_sort_left() == 0) + break; + pthread_cond_wait(&g_ls_cond, &g_ls_mutex); } pthread_mutex_unlock(&g_ls_mutex); @@ -495,13 +508,8 @@ run_sort_cycle_mt(void) for (;;) { slc = pop_ls_mt(); - if (slc == NULL) { - if (have_sort_left()) { - pthread_yield(); - continue; - } + if (slc == NULL) break; - } run_sort_level_next(slc); } } @@ -512,9 +520,7 @@ run_sort_cycle_mt(void) static void* sort_thread(void* arg) { - run_sort_cycle_mt(); - sem_post(&mtsem); return (arg); @@ -610,8 +616,7 @@ run_top_sort_level(struct sort_level *sl) pthread_t pth; pthread_attr_init(&attr); - pthread_attr_setdetachstate(&attr, - PTHREAD_DETACHED); + pthread_attr_setdetachstate(&attr, PTHREAD_DETACHED); for (;;) { int res = pthread_create(&pth, &attr, @@ -628,7 +633,7 @@ run_top_sort_level(struct sort_level *sl) pthread_attr_destroy(&attr); } - for(i = 0; i < nthreads; ++i) + for (i = 0; i < nthreads; ++i) sem_wait(&mtsem); } #endif /* defined(SORT_THREADS) */ @@ -651,7 +656,7 @@ run_sort(struct sort_list_item **base, size_t nmemb) pthread_mutexattr_settype(&mattr, PTHREAD_MUTEX_ADAPTIVE_NP); pthread_mutex_init(&g_ls_mutex, &mattr); - pthread_mutex_init(&sort_left_mutex, &mattr); + pthread_cond_init(&g_ls_cond, NULL); pthread_mutexattr_destroy(&mattr); @@ -679,7 +684,6 @@ run_sort(struct sort_list_item **base, size_t nmemb) if (nthreads > 1) { sem_destroy(&mtsem); pthread_mutex_destroy(&g_ls_mutex); - pthread_mutex_destroy(&sort_left_mutex); } nthreads = nthreads_save; #endif
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