| Message ID | 1305194086-9832-5-git-send-email-stefanha@linux.vnet.ibm.com |
|---|---|
| State | New |
| Headers | show |
terAm 12.05.2011 11:54, schrieb Stefan Hajnoczi: > This patch speeds up coroutine creation by reusing freed coroutines. > When a coroutine terminates it is placed in the pool instead of having > its resources freed. The next time a coroutine is created it can be > taken straight from the pool and requires no initialization. > > Performance results on an Intel Core2 Duo T9400 (2.53GHz) for > ./check-coroutine --benchmark-lifecycle 20000000: > > No pooling: 19.5 sec > With pooling: 1.1 sec > > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> > --- > check-coroutine.c | 2 ++ > qemu-coroutine-int.h | 2 ++ > qemu-coroutine.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- > qemu-coroutine.h | 9 +++++++++ > vl.c | 2 ++ > 5 files changed, 61 insertions(+), 3 deletions(-) > > diff --git a/check-coroutine.c b/check-coroutine.c > index 5a42c49..223c50c 100644 > --- a/check-coroutine.c > +++ b/check-coroutine.c > @@ -218,6 +218,8 @@ int main(int argc, char **argv) > }; > int i; > > + qemu_coroutine_init(); Can we use module_init instead of adding an explicit call to main()? This would prevent forgetting to add it in qemu-img and qemu-io like in this patch. Kevin
On Thu, May 12, 2011 at 11:13 AM, Kevin Wolf <kwolf@redhat.com> wrote: > terAm 12.05.2011 11:54, schrieb Stefan Hajnoczi: >> This patch speeds up coroutine creation by reusing freed coroutines. >> When a coroutine terminates it is placed in the pool instead of having >> its resources freed. The next time a coroutine is created it can be >> taken straight from the pool and requires no initialization. >> >> Performance results on an Intel Core2 Duo T9400 (2.53GHz) for >> ./check-coroutine --benchmark-lifecycle 20000000: >> >> No pooling: 19.5 sec >> With pooling: 1.1 sec >> >> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> >> --- >> check-coroutine.c | 2 ++ >> qemu-coroutine-int.h | 2 ++ >> qemu-coroutine.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- >> qemu-coroutine.h | 9 +++++++++ >> vl.c | 2 ++ >> 5 files changed, 61 insertions(+), 3 deletions(-) >> >> diff --git a/check-coroutine.c b/check-coroutine.c >> index 5a42c49..223c50c 100644 >> --- a/check-coroutine.c >> +++ b/check-coroutine.c >> @@ -218,6 +218,8 @@ int main(int argc, char **argv) >> }; >> int i; >> >> + qemu_coroutine_init(); > > Can we use module_init instead of adding an explicit call to main()? > This would prevent forgetting to add it in qemu-img and qemu-io like in > this patch. module_init what? :) qemu-img/qemu-io only init MODULE_INIT_BLOCK so we'd have to modify them anyway. I don't want to add qemu-img/qemu-io things yet because we don't have a block layer user for coroutines yet. The qcow2 patches should contain these changes. Stefan
Am 12.05.2011 12:22, schrieb Stefan Hajnoczi: > On Thu, May 12, 2011 at 11:13 AM, Kevin Wolf <kwolf@redhat.com> wrote: >> terAm 12.05.2011 11:54, schrieb Stefan Hajnoczi: >>> This patch speeds up coroutine creation by reusing freed coroutines. >>> When a coroutine terminates it is placed in the pool instead of having >>> its resources freed. The next time a coroutine is created it can be >>> taken straight from the pool and requires no initialization. >>> >>> Performance results on an Intel Core2 Duo T9400 (2.53GHz) for >>> ./check-coroutine --benchmark-lifecycle 20000000: >>> >>> No pooling: 19.5 sec >>> With pooling: 1.1 sec >>> >>> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> >>> --- >>> check-coroutine.c | 2 ++ >>> qemu-coroutine-int.h | 2 ++ >>> qemu-coroutine.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- >>> qemu-coroutine.h | 9 +++++++++ >>> vl.c | 2 ++ >>> 5 files changed, 61 insertions(+), 3 deletions(-) >>> >>> diff --git a/check-coroutine.c b/check-coroutine.c >>> index 5a42c49..223c50c 100644 >>> --- a/check-coroutine.c >>> +++ b/check-coroutine.c >>> @@ -218,6 +218,8 @@ int main(int argc, char **argv) >>> }; >>> int i; >>> >>> + qemu_coroutine_init(); >> >> Can we use module_init instead of adding an explicit call to main()? >> This would prevent forgetting to add it in qemu-img and qemu-io like in >> this patch. > > module_init what? :) qemu-img/qemu-io only init MODULE_INIT_BLOCK so > we'd have to modify them anyway. Right... I was thinking of block, but in fact coroutines are not limited to the block layer, so we would abuse it. > I don't want to add qemu-img/qemu-io things yet because we don't have > a block layer user for coroutines yet. The qcow2 patches should > contain these changes. I hope we won't forget it. A missing atexit isn't a very obvious bug. Kevin
On 05/12/2011 12:38 PM, Kevin Wolf wrote: >> I don't want to add qemu-img/qemu-io things yet because we don't have >> a block layer user for coroutines yet. The qcow2 patches should >> contain these changes. > > I hope we won't forget it. A missing atexit isn't a very obvious bug. I was going to reply that this atexit is actually useless, since memory is freed automatically at exit? Paolo
On Thu, May 12, 2011 at 12:12 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > On 05/12/2011 12:38 PM, Kevin Wolf wrote: >>> >>> I don't want to add qemu-img/qemu-io things yet because we don't have >>> a block layer user for coroutines yet. The qcow2 patches should >>> contain these changes. >> >> I hope we won't forget it. A missing atexit isn't a very obvious bug. > > I was going to reply that this atexit is actually useless, since memory is > freed automatically at exit? It's just for completeness to make tools like valgrind happy. Sure, the kernel will reclaim memory and we're just burning CPU by freeing this stuff ;). Stefan
On 05/12/2011 01:15 PM, Stefan Hajnoczi wrote: > It's just for completeness to make tools like valgrind happy. Sure, > the kernel will reclaim memory and we're just burning CPU by freeing > this stuff;). But valgrind will not complain about reachable memory still allocated at exit, at least not with the default command-line options. Paolo
On Thu, May 12, 2011 at 12:18 PM, Paolo Bonzini <pbonzini@redhat.com> wrote: > On 05/12/2011 01:15 PM, Stefan Hajnoczi wrote: >> >> It's just for completeness to make tools like valgrind happy. Sure, >> the kernel will reclaim memory and we're just burning CPU by freeing >> this stuff;). > > But valgrind will not complain about reachable memory still allocated at > exit, at least not with the default command-line options. /me is outsmarted by valgrind Then I will remove pool freeing in v3. Stefan
diff --git a/check-coroutine.c b/check-coroutine.c index 5a42c49..223c50c 100644 --- a/check-coroutine.c +++ b/check-coroutine.c @@ -218,6 +218,8 @@ int main(int argc, char **argv) }; int i; + qemu_coroutine_init(); + if (argc == 3 && strcmp(argv[1], "--benchmark-lifecycle") == 0) { benchmark_lifecycle(argv[2]); return EXIT_SUCCESS; diff --git a/qemu-coroutine-int.h b/qemu-coroutine-int.h index 71c6ee9..b264881 100644 --- a/qemu-coroutine-int.h +++ b/qemu-coroutine-int.h @@ -45,6 +45,8 @@ struct Coroutine { void *data; CoroutineEntry *entry; + QLIST_ENTRY(Coroutine) pool_next; + jmp_buf env; }; diff --git a/qemu-coroutine.c b/qemu-coroutine.c index 80bed14..cff5a4f 100644 --- a/qemu-coroutine.c +++ b/qemu-coroutine.c @@ -24,16 +24,35 @@ #include "qemu-coroutine.h" #include "qemu-coroutine-int.h" +enum { + /* Maximum free pool size prevents holding too many freed coroutines */ + POOL_MAX_SIZE = 64, +}; + +static QLIST_HEAD(, Coroutine) pool = QLIST_HEAD_INITIALIZER(&pool); +static unsigned int pool_size; static __thread Coroutine leader; static __thread Coroutine *current; -static void coroutine_terminate(Coroutine *co) +static void coroutine_delete(Coroutine *co) { - trace_qemu_coroutine_terminate(co); qemu_free(co->stack); qemu_free(co); } +static void coroutine_terminate(Coroutine *co) +{ + trace_qemu_coroutine_terminate(co); + + if (pool_size < POOL_MAX_SIZE) { + QLIST_INSERT_HEAD(&pool, co, pool_next); + co->caller = NULL; + pool_size++; + } else { + coroutine_delete(co); + } +} + static Coroutine *coroutine_new(void) { const size_t stack_size = 4 << 20; @@ -49,7 +68,15 @@ Coroutine *qemu_coroutine_create(CoroutineEntry *entry) { Coroutine *co; - co = coroutine_new(); + co = QLIST_FIRST(&pool); + + if (co) { + QLIST_REMOVE(co, pool_next); + pool_size--; + } else { + co = coroutine_new(); + } + co->entry = entry; return co; @@ -123,3 +150,19 @@ void *coroutine_fn qemu_coroutine_yield(void) self->caller = NULL; return coroutine_swap(self, to, NULL); } + +static void coroutine_free_pool(void) +{ + Coroutine *co; + Coroutine *tmp; + + QLIST_FOREACH_SAFE(co, &pool, pool_next, tmp) { + coroutine_delete(co); + } + pool_size = 0; +} + +void qemu_coroutine_init(void) +{ + atexit(coroutine_free_pool); +} diff --git a/qemu-coroutine.h b/qemu-coroutine.h index b79b4bf..0fae0a4 100644 --- a/qemu-coroutine.h +++ b/qemu-coroutine.h @@ -17,6 +17,15 @@ #include <stdbool.h> /** + * Initialize coroutine implementation + * + * This function should be called when the program is starting up. It installs + * an atexit(3) handler which will free pooled coroutines when the program + * exits. This keeps valgrind output clean. + */ +void qemu_coroutine_init(void); + +/** * Mark a function that executes in coroutine context * * Functions that execute in coroutine context cannot be called directly from diff --git a/vl.c b/vl.c index 6b9a2f6..7092c9f 100644 --- a/vl.c +++ b/vl.c @@ -145,6 +145,7 @@ int main(int argc, char **argv) #include "qemu-config.h" #include "qemu-objects.h" #include "qemu-options.h" +#include "qemu-coroutine.h" #ifdef CONFIG_VIRTFS #include "fsdev/qemu-fsdev.h" #endif @@ -1975,6 +1976,7 @@ int main(int argc, char **argv, char **envp) init_clocks(); qemu_cache_utils_init(envp); + qemu_coroutine_init(); QLIST_INIT (&vm_change_state_head); os_setup_early_signal_handling();
This patch speeds up coroutine creation by reusing freed coroutines. When a coroutine terminates it is placed in the pool instead of having its resources freed. The next time a coroutine is created it can be taken straight from the pool and requires no initialization. Performance results on an Intel Core2 Duo T9400 (2.53GHz) for ./check-coroutine --benchmark-lifecycle 20000000: No pooling: 19.5 sec With pooling: 1.1 sec Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> --- check-coroutine.c | 2 ++ qemu-coroutine-int.h | 2 ++ qemu-coroutine.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++--- qemu-coroutine.h | 9 +++++++++ vl.c | 2 ++ 5 files changed, 61 insertions(+), 3 deletions(-)