From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37612) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d2hLS-0001gi-17 for qemu-devel@nongnu.org; Mon, 24 Apr 2017 13:00:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d2hLO-00045S-47 for qemu-devel@nongnu.org; Mon, 24 Apr 2017 13:00:14 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:58463) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1d2hLN-00044t-Rg for qemu-devel@nongnu.org; Mon, 24 Apr 2017 13:00:10 -0400 Received: from pps.filterd (m0098396.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v3OGx50L001472 for ; Mon, 24 Apr 2017 13:00:08 -0400 Received: from e24smtp01.br.ibm.com (e24smtp01.br.ibm.com [32.104.18.85]) by mx0a-001b2d01.pphosted.com with ESMTP id 2a1j763cpx-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 24 Apr 2017 13:00:07 -0400 Received: from localhost by e24smtp01.br.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 24 Apr 2017 14:00:05 -0300 Received: from d24av03.br.ibm.com (d24av03.br.ibm.com [9.8.31.95]) by d24relay04.br.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v3OH03RM46268498 for ; Mon, 24 Apr 2017 14:00:03 -0300 Received: from d24av03.br.ibm.com (localhost [127.0.0.1]) by d24av03.br.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v3OH04mt021509 for ; Mon, 24 Apr 2017 14:00:04 -0300 Date: Mon, 24 Apr 2017 13:59:51 -0300 From: joserz@linux.vnet.ibm.com References: <1493044126-21488-1-git-send-email-joserz@linux.vnet.ibm.com> <20170424144552.GA6511@lemon.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170424144552.GA6511@lemon.lan> Message-Id: <20170424165950.GA10437@pacoca> Subject: Re: [Qemu-devel] [PATCH] trace: add qemu mutex lock and unlock trace events List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, stefanha@redhat.com On Mon, Apr 24, 2017 at 10:45:52PM +0800, Fam Zheng wrote: > On Mon, 04/24 11:28, Jose Ricardo Ziviani wrote: > > These trace events were very useful to help me to understand and find a > > reordering issue in vfio, for example: > > > > qemu_mutex_lock locked mutex 0x10905ad8 > > vfio_region_write (0001:03:00.0:region1+0xc0, 0x2020c, 4) > > qemu_mutex_unlock unlocked mutex 0x10905ad8 > > qemu_mutex_lock locked mutex 0x10905ad8 > > vfio_region_write (0001:03:00.0:region1+0xc4, 0xa0000, 4) > > qemu_mutex_unlock unlocked mutex 0x10905ad8 > > > > that also helped to see desired result after the fix: > > > > qemu_mutex_lock locked mutex 0x10905ad8 > > vfio_region_write (0001:03:00.0:region1+0xc0, 0x2000c, 4) > > vfio_region_write (0001:03:00.0:region1+0xc4, 0xb0000, 4) > > qemu_mutex_unlock unlocked mutex 0x10905ad8 > > > > So it could be a good idea to have these traces implemented. It's worth > > mentioning that they should be surgically enabled during the debugging, > > otherwise it'd flood the trace logs with lock/unlock messages. > > > > How to use it: > > trace-event qemu_mutex_lock on|off > > trace-event qemu_mutex_unlock on|off > > or > > trace-event qemu_mutex* on|off > > > > Signed-off-by: Jose Ricardo Ziviani > > --- > > util/qemu-thread-posix.c | 5 +++++ > > util/trace-events | 4 ++++ > > 2 files changed, 9 insertions(+) > > > > diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c > > index 73e3a0e..909c2ac 100644 > > --- a/util/qemu-thread-posix.c > > +++ b/util/qemu-thread-posix.c > > @@ -14,6 +14,7 @@ > > #include "qemu/thread.h" > > #include "qemu/atomic.h" > > #include "qemu/notify.h" > > +#include "trace.h" > > > > static bool name_threads; > > > > @@ -60,6 +61,8 @@ void qemu_mutex_lock(QemuMutex *mutex) > > err = pthread_mutex_lock(&mutex->lock); > > if (err) > > error_exit(err, __func__); > > + > > + trace_qemu_mutex_lock((void *)&mutex->lock); > > You don't need these casts as the parameter type is void * which accepts any > pointers. OK > > > } > > > > int qemu_mutex_trylock(QemuMutex *mutex) > > @@ -74,6 +77,8 @@ void qemu_mutex_unlock(QemuMutex *mutex) > > err = pthread_mutex_unlock(&mutex->lock); > > if (err) > > error_exit(err, __func__); > > + > > + trace_qemu_mutex_unlock((void *)&mutex->lock); > > } > > > > void qemu_rec_mutex_init(QemuRecMutex *mutex) > > diff --git a/util/trace-events b/util/trace-events > > index b44ef4f..65c33fe 100644 > > --- a/util/trace-events > > +++ b/util/trace-events > > @@ -55,3 +55,7 @@ lockcnt_futex_wait_prepare(const void *lockcnt, int expected, int new) "lockcnt > > lockcnt_futex_wait(const void *lockcnt, int val) "lockcnt %p waiting on %d" > > lockcnt_futex_wait_resume(const void *lockcnt, int new) "lockcnt %p after wait: %d" > > lockcnt_futex_wake(const void *lockcnt) "lockcnt %p waking up one waiter" > > + > > +# util/qemu-thread-posix.c > > +qemu_mutex_lock(void *qemu_global_mutex) "locked mutex %p" > > +qemu_mutex_unlock(void *qemu_global_mutex) "unlocked mutex %p" > > Parameter name is slightly misleading, maybe s/qemu_global_mutex/lock/ for both > lines? Great! I'll change it and send a v2. Thank for your review! > > Fam >