[Qemu-devel] [PATCH] qemu-io: add option to enable tracing

[Qemu-devel] [PATCH] qemu-io: add option to enable tracing

[Stefan Hajnoczi]

It can be useful to enable QEMU tracing when trying out block layer
interfaces via qemu-io.  Tracing can be enabled using the new -t FILE
option where the given file contains a list of trace events to enable
(just like the qemu --trace events=FILE option).

  $ echo qemu_vfree >my-events
  $ ./qemu-io -t my-events ...

Remember to use ./configure --enable-trace-backend=BACKEND when building
qemu-io.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 qemu-io.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/qemu-io.c b/qemu-io.c
index ffa62fb..ad91fd6 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -17,6 +17,7 @@
 #include "qemu-common.h"
 #include "block_int.h"
 #include "cmd.h"
+#include "trace/control.h"
 
 #define VERSION	"0.0.1"
 
@@ -1722,6 +1723,7 @@ static void usage(const char *name)
 "  -g, --growable       allow file to grow (only applies to protocols)\n"
 "  -m, --misalign       misalign allocations for O_DIRECT\n"
 "  -k, --native-aio     use kernel AIO implementation (on Linux only)\n"
+"  -t, --trace FILE     enable trace events listed in the given file\n"
 "  -h, --help           display this help and exit\n"
 "  -V, --version        output version information and exit\n"
 "\n",
@@ -1733,7 +1735,7 @@ int main(int argc, char **argv)
 {
     int readonly = 0;
     int growable = 0;
-    const char *sopt = "hVc:rsnmgk";
+    const char *sopt = "hVc:rsnmgkt:";
     const struct option lopt[] = {
         { "help", 0, NULL, 'h' },
         { "version", 0, NULL, 'V' },
@@ -1745,6 +1747,7 @@ int main(int argc, char **argv)
         { "misalign", 0, NULL, 'm' },
         { "growable", 0, NULL, 'g' },
         { "native-aio", 0, NULL, 'k' },
+        { "trace", 1, NULL, 't' },
         { NULL, 0, NULL, 0 }
     };
     int c;
@@ -1776,6 +1779,9 @@ int main(int argc, char **argv)
         case 'k':
             flags |= BDRV_O_NATIVE_AIO;
             break;
+        case 't':
+            trace_backend_init(optarg, NULL);
+            break;
         case 'V':
             printf("%s version %s\n", progname, VERSION);
             exit(0);
-- 
1.7.7.3

Re: [Qemu-devel] [PATCH] qemu-io: add option to enable tracing

[Stefan Hajnoczi]

On Wed, Dec 21, 2011 at 3:35 PM, Stefan Hajnoczi
<stefanha@linux.vnet.ibm.com> wrote:

Ping?  Do you want to take this through the block tree?

> It can be useful to enable QEMU tracing when trying out block layer
> interfaces via qemu-io.  Tracing can be enabled using the new -t FILE
> option where the given file contains a list of trace events to enable
> (just like the qemu --trace events=FILE option).
>
>  $ echo qemu_vfree >my-events
>  $ ./qemu-io -t my-events ...
>
> Remember to use ./configure --enable-trace-backend=BACKEND when building
> qemu-io.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> ---
>  qemu-io.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
>
> diff --git a/qemu-io.c b/qemu-io.c
> index ffa62fb..ad91fd6 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -17,6 +17,7 @@
>  #include "qemu-common.h"
>  #include "block_int.h"
>  #include "cmd.h"
> +#include "trace/control.h"
>
>  #define VERSION        "0.0.1"
>
> @@ -1722,6 +1723,7 @@ static void usage(const char *name)
>  "  -g, --growable       allow file to grow (only applies to protocols)\n"
>  "  -m, --misalign       misalign allocations for O_DIRECT\n"
>  "  -k, --native-aio     use kernel AIO implementation (on Linux only)\n"
> +"  -t, --trace FILE     enable trace events listed in the given file\n"
>  "  -h, --help           display this help and exit\n"
>  "  -V, --version        output version information and exit\n"
>  "\n",
> @@ -1733,7 +1735,7 @@ int main(int argc, char **argv)
>  {
>     int readonly = 0;
>     int growable = 0;
> -    const char *sopt = "hVc:rsnmgk";
> +    const char *sopt = "hVc:rsnmgkt:";
>     const struct option lopt[] = {
>         { "help", 0, NULL, 'h' },
>         { "version", 0, NULL, 'V' },
> @@ -1745,6 +1747,7 @@ int main(int argc, char **argv)
>         { "misalign", 0, NULL, 'm' },
>         { "growable", 0, NULL, 'g' },
>         { "native-aio", 0, NULL, 'k' },
> +        { "trace", 1, NULL, 't' },
>         { NULL, 0, NULL, 0 }
>     };
>     int c;
> @@ -1776,6 +1779,9 @@ int main(int argc, char **argv)
>         case 'k':
>             flags |= BDRV_O_NATIVE_AIO;
>             break;
> +        case 't':
> +            trace_backend_init(optarg, NULL);
> +            break;
>         case 'V':
>             printf("%s version %s\n", progname, VERSION);
>             exit(0);
> --
> 1.7.7.3
>
>

Re: [Qemu-devel] [PATCH] qemu-io: add option to enable tracing

[Kevin Wolf]

Am 12.03.2012 12:39, schrieb Stefan Hajnoczi:
> On Wed, Dec 21, 2011 at 3:35 PM, Stefan Hajnoczi
> <stefanha@linux.vnet.ibm.com> wrote:
> 
> Ping?  Do you want to take this through the block tree?

Sorry, I completely missed this one.

>> It can be useful to enable QEMU tracing when trying out block layer
>> interfaces via qemu-io.  Tracing can be enabled using the new -t FILE
>> option where the given file contains a list of trace events to enable
>> (just like the qemu --trace events=FILE option).
>>
>>  $ echo qemu_vfree >my-events
>>  $ ./qemu-io -t my-events ...
>>
>> Remember to use ./configure --enable-trace-backend=BACKEND when building
>> qemu-io.
>>
>> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
>> ---
>>  qemu-io.c |    8 +++++++-
>>  1 files changed, 7 insertions(+), 1 deletions(-)
>>
>> diff --git a/qemu-io.c b/qemu-io.c
>> index ffa62fb..ad91fd6 100644
>> --- a/qemu-io.c
>> +++ b/qemu-io.c
>> @@ -17,6 +17,7 @@
>>  #include "qemu-common.h"
>>  #include "block_int.h"
>>  #include "cmd.h"
>> +#include "trace/control.h"
>>
>>  #define VERSION        "0.0.1"
>>
>> @@ -1722,6 +1723,7 @@ static void usage(const char *name)
>>  "  -g, --growable       allow file to grow (only applies to protocols)\n"
>>  "  -m, --misalign       misalign allocations for O_DIRECT\n"
>>  "  -k, --native-aio     use kernel AIO implementation (on Linux only)\n"
>> +"  -t, --trace FILE     enable trace events listed in the given file\n"
>>  "  -h, --help           display this help and exit\n"
>>  "  -V, --version        output version information and exit\n"
>>  "\n",
>> @@ -1733,7 +1735,7 @@ int main(int argc, char **argv)
>>  {
>>     int readonly = 0;
>>     int growable = 0;
>> -    const char *sopt = "hVc:rsnmgk";
>> +    const char *sopt = "hVc:rsnmgkt:";
>>     const struct option lopt[] = {
>>         { "help", 0, NULL, 'h' },
>>         { "version", 0, NULL, 'V' },
>> @@ -1745,6 +1747,7 @@ int main(int argc, char **argv)
>>         { "misalign", 0, NULL, 'm' },
>>         { "growable", 0, NULL, 'g' },
>>         { "native-aio", 0, NULL, 'k' },
>> +        { "trace", 1, NULL, 't' },
>>         { NULL, 0, NULL, 0 }
>>     };
>>     int c;
>> @@ -1776,6 +1779,9 @@ int main(int argc, char **argv)
>>         case 'k':
>>             flags |= BDRV_O_NATIVE_AIO;
>>             break;
>> +        case 't':
>> +            trace_backend_init(optarg, NULL);
>> +            break;

vl.c checks the return value of trace_backend_init. Shouldn't we do the
same here?

Also, I was considering adding a -t for the cache mode (option name for
consistency with qemu-img). Conversely, we'll probably want to add a
tracing option to qemu-img and -t isn't available any more there. Maybe
we should use a different letter?

Kevin

Re: [Qemu-devel] [PATCH] qemu-io: add option to enable tracing

[Stefan Hajnoczi]

On Mon, Mar 12, 2012 at 11:49 AM, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 12.03.2012 12:39, schrieb Stefan Hajnoczi:
>> On Wed, Dec 21, 2011 at 3:35 PM, Stefan Hajnoczi
>> <stefanha@linux.vnet.ibm.com> wrote:
>>> @@ -1776,6 +1779,9 @@ int main(int argc, char **argv)
>>>         case 'k':
>>>             flags |= BDRV_O_NATIVE_AIO;
>>>             break;
>>> +        case 't':
>>> +            trace_backend_init(optarg, NULL);
>>> +            break;
>
> vl.c checks the return value of trace_backend_init. Shouldn't we do the
> same here?

ok

> Also, I was considering adding a -t for the cache mode (option name for
> consistency with qemu-img). Conversely, we'll probably want to add a
> tracing option to qemu-img and -t isn't available any more there. Maybe
> we should use a different letter?

ok

Stefan