[Mesa-dev] pipebuffer: Use pipe_condvar instead of ifdef'd sys_yield()

[nobled]

Well, that's why I sent the "Implement pipe_condvar on win32" and "on
Windows Vista" patches first. With the first patch, the pipebuffer
code will do on Windows exactly what it already does right now on
Unix-- unlock the mutex, wait for other threads, then try to lock it
again. pipe_condvar on Windows (or any other platform) will *work*, it
just won't be very efficient.

On Tue, Jul 6, 2010 at 6:46 AM, José Fonseca <jfonseca at vmware.com> wrote:
> The patch looks good, but we don't support pipe_condvar on Windows yet.
> I'd prefer to see the commit deferred until we do.
>
> Any takers to implement pipe_condvar on Windows? There's even a nice
> tutorial on http://locklessinc.com/articles/pthreads_on_windows/
>
> Jose
>
> On Mon, 2010-07-05 at 09:53 -0700, nobled wrote:
>> This way there's fewer ifdef's *and* less busy-waiting.
>> ---
>>  .../auxiliary/pipebuffer/pb_buffer_fenced.c        |   19 +++++++------------
>>  1 files changed, 7 insertions(+), 12 deletions(-)
>>
>> diff --git a/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
>> b/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
>> index d6cf640..db3617e 100644
>> --- a/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
>> +++ b/src/gallium/auxiliary/pipebuffer/pb_buffer_fenced.c
>> @@ -34,13 +34,6 @@
>>   */
>>
>>
>> -#include "pipe/p_config.h"
>> -
>> -#if defined(PIPE_OS_LINUX) || defined(PIPE_OS_BSD) || defined(PIPE_OS_SOLARIS)
>> -#include <unistd.h>
>> -#include <sched.h>
>> -#endif
>> -
>>  #include "pipe/p_compiler.h"
>>  #include "pipe/p_defines.h"
>>  #include "util/u_debug.h"
>> @@ -81,6 +74,7 @@ struct fenced_manager
>>      * Following members are mutable and protected by this mutex.
>>      */
>>     pipe_mutex mutex;
>> +   pipe_condvar zero_fenced;
>>
>>     /**
>>      * Fenced buffer list.
>> @@ -307,6 +301,8 @@
>>     LIST_DEL(&fenced_buf->head);
>>     assert(fenced_mgr->num_fenced);
>>     --fenced_mgr->num_fenced;
>> +   if (fenced_mgr->num_fenced == 0)
>> +      pipe_condvar_broadcast(fenced_mgr->zero_fenced);
>>
>>     LIST_ADDTAIL(&fenced_buf->head, &fenced_mgr->unfenced);
>>     ++fenced_mgr->num_unfenced;
>> @@ -1008,13 +1004,10 @@ fenced_bufmgr_destroy(struct pb_manager *mgr)
>>
>>     /* Wait on outstanding fences */
>>     while (fenced_mgr->num_fenced) {
>> -      pipe_mutex_unlock(fenced_mgr->mutex);
>> -#if defined(PIPE_OS_LINUX) || defined(PIPE_OS_BSD) || defined(PIPE_OS_SOLARIS)
>> -      sched_yield();
>> -#endif
>> -      pipe_mutex_lock(fenced_mgr->mutex);
>>        while(fenced_manager_check_signalled_locked(fenced_mgr, TRUE))
>>           ;
>> +      if (fenced_mgr->num_fenced)
>> +         pipe_condvar_wait(fenced_mgr->zero_fenced, fenced_mgr->mutex);
>>     }
>>
>>  #ifdef DEBUG
>> @@ -1023,6 +1016,7 @@ fenced_bufmgr_destroy(struct pb_manager *mgr)
>>
>>     pipe_mutex_unlock(fenced_mgr->mutex);
>>     pipe_mutex_destroy(fenced_mgr->mutex);
>> +   pipe_condvar_destroy(fenced_mgr->zero_fenced);
>>
>>     if(fenced_mgr->provider)
>>        fenced_mgr->provider->destroy(fenced_mgr->provider);
>> @@ -1063,6 +1057,7 @@ fenced_bufmgr_create(struct pb_manager *provider,
>>     LIST_INITHEAD(&fenced_mgr->unfenced);
>>     fenced_mgr->num_unfenced = 0;
>>
>> +   pipe_condvar_init(fenced_mgr->zero_fenced);
>>     pipe_mutex_init(fenced_mgr->mutex);
>>
>>     return &fenced_mgr->base;
>
>