| Message ID | 1404395521-11158-2-git-send-email-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 07/03/2014 07:52 AM, Stefan Hajnoczi wrote: > Allow coroutine users to adjust the pool size. For example, if the > guest has multiple emulated disk drives we should keep around more > coroutines. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > include/block/coroutine.h | 11 +++++++++++ > qemu-coroutine.c | 25 +++++++++++++++++++------ > 2 files changed, 30 insertions(+), 6 deletions(-) > > + > +void qemu_coroutine_adjust_pool_size(int n) > +{ > + qemu_mutex_lock(&pool_lock); > + > + pool_max_size += n; Where do you check that this doesn't fall below a bare-minimum acceptable level? Is it worth assert(pool_max_size >= 64)?
On Thu, Jul 3, 2014 at 3:59 PM, Eric Blake <eblake@redhat.com> wrote: > On 07/03/2014 07:52 AM, Stefan Hajnoczi wrote: >> Allow coroutine users to adjust the pool size. For example, if the >> guest has multiple emulated disk drives we should keep around more >> coroutines. >> >> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> >> --- >> include/block/coroutine.h | 11 +++++++++++ >> qemu-coroutine.c | 25 +++++++++++++++++++------ >> 2 files changed, 30 insertions(+), 6 deletions(-) >> > >> + >> +void qemu_coroutine_adjust_pool_size(int n) >> +{ >> + qemu_mutex_lock(&pool_lock); >> + >> + pool_max_size += n; > > Where do you check that this doesn't fall below a bare-minimum > acceptable level? Is it worth assert(pool_max_size >= 64)? I don't. I think you are right; it's worth checking. Stefan
diff --git a/include/block/coroutine.h b/include/block/coroutine.h index a1797ae..07eeb3c 100644 --- a/include/block/coroutine.h +++ b/include/block/coroutine.h @@ -223,4 +223,15 @@ void coroutine_fn co_aio_sleep_ns(AioContext *ctx, QEMUClockType type, * Note that this function clobbers the handlers for the file descriptor. */ void coroutine_fn yield_until_fd_readable(int fd); + +/** + * Add or subtract from the coroutine pool size + * + * The coroutine implementation keeps a pool of coroutines to be reused by + * qemu_coroutine_create(). This makes coroutine creation cheap. Heavy + * coroutine users should call this to reserve pool space. Call it again with + * a negative number to release pool space. + */ +void qemu_coroutine_adjust_pool_size(int n); + #endif /* QEMU_COROUTINE_H */ diff --git a/qemu-coroutine.c b/qemu-coroutine.c index 4708521..d94234a 100644 --- a/qemu-coroutine.c +++ b/qemu-coroutine.c @@ -18,15 +18,11 @@ #include "block/coroutine.h" #include "block/coroutine_int.h" -enum { - /* Maximum free pool size prevents holding too many freed coroutines */ - POOL_MAX_SIZE = 64, -}; - /** Free list to speed up creation */ static QemuMutex pool_lock; static QSLIST_HEAD(, Coroutine) pool = QSLIST_HEAD_INITIALIZER(pool); static unsigned int pool_size; +static unsigned int pool_max_size = 64; Coroutine *qemu_coroutine_create(CoroutineEntry *entry) { @@ -55,7 +51,7 @@ static void coroutine_delete(Coroutine *co) { if (CONFIG_COROUTINE_POOL) { qemu_mutex_lock(&pool_lock); - if (pool_size < POOL_MAX_SIZE) { + if (pool_size < pool_max_size) { QSLIST_INSERT_HEAD(&pool, co, pool_next); co->caller = NULL; pool_size++; @@ -137,3 +133,20 @@ void coroutine_fn qemu_coroutine_yield(void) self->caller = NULL; coroutine_swap(self, to); } + +void qemu_coroutine_adjust_pool_size(int n) +{ + qemu_mutex_lock(&pool_lock); + + pool_max_size += n; + + /* Trim oversized pool down to new max */ + while (pool_size > pool_max_size) { + Coroutine *co = QSLIST_FIRST(&pool); + QSLIST_REMOVE_HEAD(&pool, pool_next); + pool_size--; + qemu_coroutine_delete(co); + } + + qemu_mutex_unlock(&pool_lock); +}
Allow coroutine users to adjust the pool size. For example, if the guest has multiple emulated disk drives we should keep around more coroutines. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- include/block/coroutine.h | 11 +++++++++++ qemu-coroutine.c | 25 +++++++++++++++++++------ 2 files changed, 30 insertions(+), 6 deletions(-)