On 2011-09-21 15:57, Kevin Wolf wrote:
> Am 20.09.2011 18:53, schrieb Jan Kiszka:
>> Although there is nothing to wrap for non-POSIX here, redirecting thread
>> and synchronization services to our core simplifies managements jobs
>> like scheduling parameter adjustment. It also frees compat AIO from some
>> duplicate code (/wrt qemu-thread).
>>
>> CC: Kevin Wolf <kw...@redhat.com>
>> Signed-off-by: Jan Kiszka <jan.kis...@siemens.com>
>> ---
>> posix-aio-compat.c | 115
>> ++++++++++++++-------------------------------------
>> 1 files changed, 32 insertions(+), 83 deletions(-)
>>
>> diff --git a/posix-aio-compat.c b/posix-aio-compat.c
>> index d3c1174..0715aba 100644
>> --- a/posix-aio-compat.c
>> +++ b/posix-aio-compat.c
>> @@ -13,7 +13,6 @@
>>
>> #include <sys/ioctl.h>
>> #include <sys/types.h>
>> -#include <pthread.h>
>> #include <unistd.h>
>> #include <errno.h>
>> #include <time.h>
>> @@ -27,9 +26,12 @@
>> #include "qemu-common.h"
>> #include "trace.h"
>> #include "block_int.h"
>> +#include "qemu-thread.h"
>>
>> #include "block/raw-posix-aio.h"
>>
>> +#define AIO_THREAD_IDLE_TIMEOUT 10000 /* 10 s */
>> +
>> static void do_spawn_thread(void);
>>
>> struct qemu_paiocb {
>> @@ -57,10 +59,9 @@ typedef struct PosixAioState {
>> } PosixAioState;
>>
>>
>> -static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
>> -static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
>> -static pthread_t thread_id;
>> -static pthread_attr_t attr;
>> +static QemuMutex lock;
>> +static QemuCond cond;
>> +static QemuThread thread;
>> static int max_threads = 64;
>> static int cur_threads = 0;
>> static int idle_threads = 0;
>> @@ -86,39 +87,6 @@ static void die(const char *what)
>> die2(errno, what);
>> }
>>
>> -static void mutex_lock(pthread_mutex_t *mutex)
>> -{
>> - int ret = pthread_mutex_lock(mutex);
>> - if (ret) die2(ret, "pthread_mutex_lock");
>> -}
>> -
>> -static void mutex_unlock(pthread_mutex_t *mutex)
>> -{
>> - int ret = pthread_mutex_unlock(mutex);
>> - if (ret) die2(ret, "pthread_mutex_unlock");
>> -}
>> -
>> -static int cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
>> - struct timespec *ts)
>> -{
>> - int ret = pthread_cond_timedwait(cond, mutex, ts);
>> - if (ret && ret != ETIMEDOUT) die2(ret, "pthread_cond_timedwait");
>> - return ret;
>> -}
>> -
>> -static void cond_signal(pthread_cond_t *cond)
>> -{
>> - int ret = pthread_cond_signal(cond);
>> - if (ret) die2(ret, "pthread_cond_signal");
>> -}
>> -
>> -static void thread_create(pthread_t *thread, pthread_attr_t *attr,
>> - void *(*start_routine)(void*), void *arg)
>> -{
>> - int ret = pthread_create(thread, attr, start_routine, arg);
>> - if (ret) die2(ret, "pthread_create");
>> -}
>> -
>> static ssize_t handle_aiocb_ioctl(struct qemu_paiocb *aiocb)
>> {
>> int ret;
>> @@ -311,27 +279,22 @@ static void posix_aio_notify_event(void);
>>
>> static void *aio_thread(void *unused)
>> {
>> - mutex_lock(&lock);
>> + qemu_mutex_lock(&lock);
>> pending_threads--;
>> - mutex_unlock(&lock);
>> + qemu_mutex_unlock(&lock);
>> do_spawn_thread();
>>
>> while (1) {
>> struct qemu_paiocb *aiocb;
>> - ssize_t ret = 0;
>> - qemu_timeval tv;
>> - struct timespec ts;
>> -
>> - qemu_gettimeofday(&tv);
>> - ts.tv_sec = tv.tv_sec + 10;
>> - ts.tv_nsec = 0;
>> + bool timed_out = false;
>> + ssize_t ret;
>>
>> - mutex_lock(&lock);
>> + qemu_mutex_lock(&lock);
>>
>> - while (QTAILQ_EMPTY(&request_list) &&
>> - !(ret == ETIMEDOUT)) {
>> + while (QTAILQ_EMPTY(&request_list) && !timed_out) {
>> idle_threads++;
>> - ret = cond_timedwait(&cond, &lock, &ts);
>> + timed_out = qemu_cond_timedwait(&cond, &lock,
>> + AIO_THREAD_IDLE_TIMEOUT) != 0;
>
> Maybe I'm confused by too many negations, but isn't this the wrong way
> round?
You mean design-wise? Maybe. In any case, I think this code would also
win if we just do
if (timed_out)
break;
in the loop instead of testing the inverse on entry.
>
> + err = pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
> + if (err && err != ETIMEDOUT) {
> + error_exit(err, __func__);
> + }
> + return err == 0;
>
> So if there was an timeout, qemu_cond_timedwait returns 0 (should it
> return a bool? Also documenting the return value wouldn't hurt) and
> timed_out becomes false (0 != 0).
Will switch to a bool return code (and document it).
Thanks,
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
