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We do not need to wait for the main process to be ready to receive the data from the threads before shutting them down.

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Only wait for the "ready" semaphore if we've failed to decompress in parallel.
This affords a small speedup on decompression.
This commit is contained in:
Con Kolivas 2011-02-06 11:58:47 +11:00
parent 8d110e3366
commit 6b73eb1394
1 changed files with 12 additions and 15 deletions
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27
stream.c
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@ -1126,24 +1126,20 @@ retry:
if (waited) if (waited)
fatal("Failed to decompress in ucompthread\n"); fatal("Failed to decompress in ucompthread\n");
print_maxverbose("Unable to decompress in parallel, waiting for previous thread to complete before trying again\n"); print_maxverbose("Unable to decompress in parallel, waiting for previous thread to complete before trying again\n");
} /* This "ready" tells this thread that we're ready to receive
* its data. We do not strictly need to wait for this, so it's
/* First ready, are up to this thread yet? */ * used when decompression fails due to inadequate memory to
if (!waited) { * try again serialised. */
wait_sem(&uci->ready); wait_sem(&uci->ready);
waited = 1; waited = 1;
}
if (ret)
goto retry; goto retry;
}
/* This complete tells the main thread that this thread has its /* This "complete" tells the main thread that this thread has its
* decompressed data ready */ * decompressed data ready */
post_sem(&uci->complete); post_sem(&uci->complete);
/* Second ready, the buffer has been grabbed by the main thread so this
* thread can exit */
wait_sem(&uci->ready);
print_maxverbose("Thread %ld returning %lld uncompressed bytes from stream %d\n", i, uci->u_len, uci->stream); print_maxverbose("Thread %ld decompressed %lld bytes from stream %d\n", i, uci->u_len, uci->stream);
return 0; return 0;
} }
@ -1230,21 +1226,22 @@ fill_another:
} }
} }
out: out:
/* This "ready" tells the decompression thread we're up to it */ /* "ready" tells the decompression thread we're ready for its data */
post_sem(&ucthread[s->unext_thread].ready); post_sem(&ucthread[s->unext_thread].ready);
/* This "complete" is the deco thread telling us it's finished /* This "complete" is the deco thread telling us it's finished
* decompressing data */ * decompressing data */
wait_sem(&ucthread[s->unext_thread].complete); wait_sem(&ucthread[s->unext_thread].complete);
print_maxverbose("Taking decompressed data from thread %ld\n", s->unext_thread);
s->buf = ucthread[s->unext_thread].s_buf; s->buf = ucthread[s->unext_thread].s_buf;
s->buflen = ucthread[s->unext_thread].u_len; s->buflen = ucthread[s->unext_thread].u_len;
s->bufp = 0; s->bufp = 0;
/* This "ready" tells the decompression thread we've taken the buffer so
* it can exit */
post_sem(&ucthread[s->unext_thread].ready);
join_pthread(threads[s->unext_thread], NULL); join_pthread(threads[s->unext_thread], NULL);
post_sem(&ucthread[s->unext_thread].free); post_sem(&ucthread[s->unext_thread].free);
/* As the ready semaphore may or may not have been waited on in
* ucompthread, we reset it regardless. */
init_sem(&ucthread[s->unext_thread].ready);
if (++s->unext_thread == s->base_thread + s->total_threads) if (++s->unext_thread == s->base_thread + s->total_threads)
s->unext_thread = s->base_thread; s->unext_thread = s->base_thread;