Am 12.03.2012 12:39, schrieb Stefan Hajnoczi:
> On Wed, Dec 21, 2011 at 3:35 PM, Stefan Hajnoczi
> <stefa...@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 <stefa...@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
