[Qemu-devel] [PATCH] block: move trace probes into bdrv_co_preadv|pwritev

[Qemu-devel] [PATCH] block: move trace probes into bdrv_co_preadv|pwritev

[Daniel P. Berrange]

There are trace probes in bdrv_co_readv|writev, however, the
block drivers are being gradually moved over to using the
bdrv_co_preadv|pwritev functions instead. As a result some
block drivers miss the current probes. Move the probes
into bdrv_co_preadv|pwritev instead, so that they are triggered
by more (all?) I/O code paths.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 block/io.c         | 8 ++++----
 block/trace-events | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/io.c b/block/io.c
index d9dc822173..26003814eb 100644
--- a/block/io.c
+++ b/block/io.c
@@ -1135,6 +1135,8 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
     bool use_local_qiov = false;
     int ret;
 
+    trace_bdrv_co_preadv(child->bs, offset, bytes, flags);
+
     if (!drv) {
         return -ENOMEDIUM;
     }
@@ -1207,8 +1209,6 @@ static int coroutine_fn bdrv_co_do_readv(BdrvChild *child,
 int coroutine_fn bdrv_co_readv(BdrvChild *child, int64_t sector_num,
                                int nb_sectors, QEMUIOVector *qiov)
 {
-    trace_bdrv_co_readv(child->bs, sector_num, nb_sectors);
-
     return bdrv_co_do_readv(child, sector_num, nb_sectors, qiov, 0);
 }
 
@@ -1526,6 +1526,8 @@ int coroutine_fn bdrv_co_pwritev(BdrvChild *child,
     bool use_local_qiov = false;
     int ret;
 
+    trace_bdrv_co_pwritev(child->bs, offset, bytes, flags);
+
     if (!bs->drv) {
         return -ENOMEDIUM;
     }
@@ -1660,8 +1662,6 @@ static int coroutine_fn bdrv_co_do_writev(BdrvChild *child,
 int coroutine_fn bdrv_co_writev(BdrvChild *child, int64_t sector_num,
     int nb_sectors, QEMUIOVector *qiov)
 {
-    trace_bdrv_co_writev(child->bs, sector_num, nb_sectors);
-
     return bdrv_co_do_writev(child, sector_num, nb_sectors, qiov, 0);
 }
 
diff --git a/block/trace-events b/block/trace-events
index 071a8d77ba..25dd5a3026 100644
--- a/block/trace-events
+++ b/block/trace-events
@@ -9,8 +9,8 @@ blk_co_preadv(void *blk, void *bs, int64_t offset, unsigned int bytes, int flags
 blk_co_pwritev(void *blk, void *bs, int64_t offset, unsigned int bytes, int flags) "blk %p bs %p offset %"PRId64" bytes %u flags 0x%x"
 
 # block/io.c
-bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
-bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
+bdrv_co_preadv(void *bs, int64_t offset, int64_t nbytes, unsigned int flags) "bs %p offset %"PRId64" nbytes %"PRId64" flags 0x%x"
+bdrv_co_pwritev(void *bs, int64_t offset, int64_t nbytes, unsigned int flags) "bs %p offset %"PRId64" nbytes %"PRId64" flags 0x%x"
 bdrv_co_pwrite_zeroes(void *bs, int64_t offset, int count, int flags) "bs %p offset %"PRId64" count %d flags 0x%x"
 bdrv_co_do_copy_on_readv(void *bs, int64_t offset, unsigned int bytes, int64_t cluster_offset, unsigned int cluster_bytes) "bs %p offset %"PRId64" bytes %u cluster_offset %"PRId64" cluster_bytes %u"
 
-- 
2.13.3

Re: [Qemu-devel] [Qemu-block] [PATCH for-2.10] block: move trace probes into bdrv_co_preadv|pwritev

[Eric Blake]

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On 08/04/2017 05:50 AM, Daniel P. Berrange wrote:
> There are trace probes in bdrv_co_readv|writev, however, the
> block drivers are being gradually moved over to using the
> bdrv_co_preadv|pwritev functions instead. As a result some
> block drivers miss the current probes. Move the probes
> into bdrv_co_preadv|pwritev instead, so that they are triggered
> by more (all?) I/O code paths.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>  block/io.c         | 8 ++++----
>  block/trace-events | 4 ++--
>  2 files changed, 6 insertions(+), 6 deletions(-)

Arguably, the traces are broken, so this is a bug fix worthy of 2.10.

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org


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Re: [Qemu-devel] [PATCH] block: move trace probes into bdrv_co_preadv|pwritev

[Stefan Hajnoczi]

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On Fri, Aug 04, 2017 at 11:50:36AM +0100, Daniel P. Berrange wrote:
> There are trace probes in bdrv_co_readv|writev, however, the
> block drivers are being gradually moved over to using the
> bdrv_co_preadv|pwritev functions instead. As a result some
> block drivers miss the current probes. Move the probes
> into bdrv_co_preadv|pwritev instead, so that they are triggered
> by more (all?) I/O code paths.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>  block/io.c         | 8 ++++----
>  block/trace-events | 4 ++--
>  2 files changed, 6 insertions(+), 6 deletions(-)

Thanks, applied to my tracing tree:
https://github.com/stefanha/qemu/commits/tracing

Stefan

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