From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60352) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZIDUH-0008OQ-8e for qemu-devel@nongnu.org; Thu, 23 Jul 2015 06:12:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZIDUB-0001zm-Ug for qemu-devel@nongnu.org; Thu, 23 Jul 2015 06:12:25 -0400 Received: from relay.parallels.com ([195.214.232.42]:35747) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZIDUB-0001xJ-Ek for qemu-devel@nongnu.org; Thu, 23 Jul 2015 06:12:19 -0400 Message-ID: <55B0BDED.6000006@parallels.com> Date: Thu, 23 Jul 2015 13:11:57 +0300 From: "Denis V. Lunev" MIME-Version: 1.0 References: <1437143029-12100-1-git-send-email-stefanha@redhat.com> <1437143029-12100-2-git-send-email-stefanha@redhat.com> <55B0BD55.4010600@de.ibm.com> In-Reply-To: <55B0BD55.4010600@de.ibm.com> Content-Type: multipart/alternative; boundary="------------070909060002040009090908" Subject: Re: [Qemu-devel] [PATCH v2 1/2] raw-posix: warn about BDRV_O_NATIVE_AIO if libaio is unavailable List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christian Borntraeger , Stefan Hajnoczi , qemu-devel@nongnu.org Cc: Kevin Wolf , Markus Armbruster , qemu-block@nongnu.org --------------070909060002040009090908 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit On 07/23/2015 01:09 PM, Christian Borntraeger wrote: > Am 17.07.2015 um 16:23 schrieb Stefan Hajnoczi: >> raw-posix.c silently ignores BDRV_O_NATIVE_AIO if libaio is unavailable. >> It is confusing when aio=native performance is identical to aio=threads >> because the binary was accidentally built without libaio. >> >> Print a deprecation warning if -drive aio=native is used with a binary >> that does not support libaio. There are probably users using aio=native >> who would be inconvenienced if QEMU suddenly refused to start their >> guests. In the future this will become an error. >> >> Signed-off-by: Stefan Hajnoczi > had that myself on a freshly installed system without libaio-devel. > Acked-by: Christian Borntraeger > > > Another thing. Would it make sense to change the default to aio=native somewhen? > From what I can tell this seems to outperform aio=threads in most cases. > this seems a good idea to me, we are always changing from threads to native in our installations >> --- >> block/raw-posix.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/block/raw-posix.c b/block/raw-posix.c >> index 855febe..e09019c 100644 >> --- a/block/raw-posix.c >> +++ b/block/raw-posix.c >> @@ -519,7 +519,16 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, >> "future QEMU versions.\n", >> bs->filename); >> } >> -#endif >> +#else >> + if (bdrv_flags & BDRV_O_NATIVE_AIO) { >> + error_printf("WARNING: aio=native was specified for '%s', but " >> + "is not supported in this build. Falling back to " >> + "aio=threads.\n" >> + " This will become an error condition in " >> + "future QEMU versions.\n", >> + bs->filename); >> + } >> +#endif /* !defined(CONFIG_LINUX_AIO) */ >> >> s->has_discard = true; >> s->has_write_zeroes = true; >> > --------------070909060002040009090908 Content-Type: text/html; charset="windows-1252" Content-Transfer-Encoding: 7bit
On 07/23/2015 01:09 PM, Christian Borntraeger wrote:
Am 17.07.2015 um 16:23 schrieb Stefan Hajnoczi:

raw-posix.c silently ignores BDRV_O_NATIVE_AIO if libaio is unavailable.
It is confusing when aio=native performance is identical to aio=threads
because the binary was accidentally built without libaio.

Print a deprecation warning if -drive aio=native is used with a binary
that does not support libaio.  There are probably users using aio=native
who would be inconvenienced if QEMU suddenly refused to start their
guests.  In the future this will become an error.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

had that myself on a freshly installed system without libaio-devel.
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>


Another thing. Would it make sense to change the default to aio=native somewhen?
>>From what I can tell this seems to outperform aio=threads in most cases.

this seems a good idea to me, we are always changing
from threads to native in our installations


      

        
---
 block/raw-posix.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/block/raw-posix.c b/block/raw-posix.c
index 855febe..e09019c 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -519,7 +519,16 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
                      "future QEMU versions.\n",
                      bs->filename);
     }
-#endif
+#else
+    if (bdrv_flags & BDRV_O_NATIVE_AIO) {
+        error_printf("WARNING: aio=native was specified for '%s', but "
+                     "is not supported in this build. Falling back to "
+                     "aio=threads.\n"
+                     "         This will become an error condition in "
+                     "future QEMU versions.\n",
+                     bs->filename);
+    }
+#endif /* !defined(CONFIG_LINUX_AIO) */

     s->has_discard = true;
     s->has_write_zeroes = true;



      

      



    

    

  


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