Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev
On Wed, Feb 22, 2017 at 01:47:10PM +0100, Kevin Wolf wrote: > Am 17.02.2017 um 22:51 hat Jeff Cody geschrieben: > > On Fri, Feb 17, 2017 at 03:42:52PM -0600, Eric Blake wrote: > > > On 02/17/2017 03:37 PM, Jeff Cody wrote: > > > > On Fri, Feb 17, 2017 at 05:39:01PM +0100, Peter Lieven wrote: > > > >> if the passed qiov contains exactly one iov we can > > > >> pass the buffer directly. > > > >> > > > >> Signed-off-by: Peter Lieven > > > >> --- > > > >> block/nfs.c | 23 --- > > > >> 1 file changed, 16 insertions(+), 7 deletions(-) > > > >> > > > >> diff --git a/block/nfs.c b/block/nfs.c > > > >> index ab5dcc2..bb4b75f 100644 > > > >> --- a/block/nfs.c > > > >> +++ b/block/nfs.c > > > >> @@ -295,20 +295,27 @@ static int coroutine_fn > > > >> nfs_co_pwritev(BlockDriverState *bs, uint64_t offset, > > > >> NFSClient *client = bs->opaque; > > > >> NFSRPC task; > > > >> char *buf = NULL; > > > >> +bool my_buffer = false; > > > > > > > > g_free() is a nop if buf is NULL, so there is no need for the my_buffer > > > > variable & check. > > > > > > Umm, yes there is: > > > > > > >> +if (iov->niov != 1) { > > > >> +buf = g_try_malloc(bytes); > > > >> +if (bytes && buf == NULL) { > > > >> +return -ENOMEM; > > > >> +} > > > >> +qemu_iovec_to_buf(iov, 0, buf, bytes); > > > >> +my_buffer = true; > > > >> +} else { > > > >> +buf = iov->iov[0].iov_base; > > > > > > If we took the else branch, then we definitely do not want to be calling > > > g_free(buf). > > > > Doh! > > > > > > > > >> } > > > >> > > > >> -qemu_iovec_to_buf(iov, 0, buf, bytes); > > > >> - > > > >> if (nfs_pwrite_async(client->context, client->fh, > > > >> offset, bytes, buf, > > > >> nfs_co_generic_cb, &task) != 0) { > > > >> -g_free(buf); > > > >> +if (my_buffer) { > > > >> +g_free(buf); > > > >> +} > > > > > > It looks correct as-is to me. > > > > Indeed. > > > > Reviewed-by: Jeff Cody > > You gave R-b for both patches, but did not merge it - who is supposed to > do that? > I am going to do it in my next round, I was just waiting to see if there were any other comments.
Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev
Am 17.02.2017 um 22:51 hat Jeff Cody geschrieben: > On Fri, Feb 17, 2017 at 03:42:52PM -0600, Eric Blake wrote: > > On 02/17/2017 03:37 PM, Jeff Cody wrote: > > > On Fri, Feb 17, 2017 at 05:39:01PM +0100, Peter Lieven wrote: > > >> if the passed qiov contains exactly one iov we can > > >> pass the buffer directly. > > >> > > >> Signed-off-by: Peter Lieven > > >> --- > > >> block/nfs.c | 23 --- > > >> 1 file changed, 16 insertions(+), 7 deletions(-) > > >> > > >> diff --git a/block/nfs.c b/block/nfs.c > > >> index ab5dcc2..bb4b75f 100644 > > >> --- a/block/nfs.c > > >> +++ b/block/nfs.c > > >> @@ -295,20 +295,27 @@ static int coroutine_fn > > >> nfs_co_pwritev(BlockDriverState *bs, uint64_t offset, > > >> NFSClient *client = bs->opaque; > > >> NFSRPC task; > > >> char *buf = NULL; > > >> +bool my_buffer = false; > > > > > > g_free() is a nop if buf is NULL, so there is no need for the my_buffer > > > variable & check. > > > > Umm, yes there is: > > > > >> +if (iov->niov != 1) { > > >> +buf = g_try_malloc(bytes); > > >> +if (bytes && buf == NULL) { > > >> +return -ENOMEM; > > >> +} > > >> +qemu_iovec_to_buf(iov, 0, buf, bytes); > > >> +my_buffer = true; > > >> +} else { > > >> +buf = iov->iov[0].iov_base; > > > > If we took the else branch, then we definitely do not want to be calling > > g_free(buf). > > Doh! > > > > > >> } > > >> > > >> -qemu_iovec_to_buf(iov, 0, buf, bytes); > > >> - > > >> if (nfs_pwrite_async(client->context, client->fh, > > >> offset, bytes, buf, > > >> nfs_co_generic_cb, &task) != 0) { > > >> -g_free(buf); > > >> +if (my_buffer) { > > >> +g_free(buf); > > >> +} > > > > It looks correct as-is to me. > > Indeed. > > Reviewed-by: Jeff Cody You gave R-b for both patches, but did not merge it - who is supposed to do that? Kevin
Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev
On Fri, Feb 17, 2017 at 03:42:52PM -0600, Eric Blake wrote: > On 02/17/2017 03:37 PM, Jeff Cody wrote: > > On Fri, Feb 17, 2017 at 05:39:01PM +0100, Peter Lieven wrote: > >> if the passed qiov contains exactly one iov we can > >> pass the buffer directly. > >> > >> Signed-off-by: Peter Lieven > >> --- > >> block/nfs.c | 23 --- > >> 1 file changed, 16 insertions(+), 7 deletions(-) > >> > >> diff --git a/block/nfs.c b/block/nfs.c > >> index ab5dcc2..bb4b75f 100644 > >> --- a/block/nfs.c > >> +++ b/block/nfs.c > >> @@ -295,20 +295,27 @@ static int coroutine_fn > >> nfs_co_pwritev(BlockDriverState *bs, uint64_t offset, > >> NFSClient *client = bs->opaque; > >> NFSRPC task; > >> char *buf = NULL; > >> +bool my_buffer = false; > > > > g_free() is a nop if buf is NULL, so there is no need for the my_buffer > > variable & check. > > Umm, yes there is: > > >> +if (iov->niov != 1) { > >> +buf = g_try_malloc(bytes); > >> +if (bytes && buf == NULL) { > >> +return -ENOMEM; > >> +} > >> +qemu_iovec_to_buf(iov, 0, buf, bytes); > >> +my_buffer = true; > >> +} else { > >> +buf = iov->iov[0].iov_base; > > If we took the else branch, then we definitely do not want to be calling > g_free(buf). Doh! > > >> } > >> > >> -qemu_iovec_to_buf(iov, 0, buf, bytes); > >> - > >> if (nfs_pwrite_async(client->context, client->fh, > >> offset, bytes, buf, > >> nfs_co_generic_cb, &task) != 0) { > >> -g_free(buf); > >> +if (my_buffer) { > >> +g_free(buf); > >> +} > > It looks correct as-is to me. Indeed. Reviewed-by: Jeff Cody
Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev
On 02/17/2017 03:37 PM, Jeff Cody wrote: > On Fri, Feb 17, 2017 at 05:39:01PM +0100, Peter Lieven wrote: >> if the passed qiov contains exactly one iov we can >> pass the buffer directly. >> >> Signed-off-by: Peter Lieven >> --- >> block/nfs.c | 23 --- >> 1 file changed, 16 insertions(+), 7 deletions(-) >> >> diff --git a/block/nfs.c b/block/nfs.c >> index ab5dcc2..bb4b75f 100644 >> --- a/block/nfs.c >> +++ b/block/nfs.c >> @@ -295,20 +295,27 @@ static int coroutine_fn >> nfs_co_pwritev(BlockDriverState *bs, uint64_t offset, >> NFSClient *client = bs->opaque; >> NFSRPC task; >> char *buf = NULL; >> +bool my_buffer = false; > > g_free() is a nop if buf is NULL, so there is no need for the my_buffer > variable & check. Umm, yes there is: >> +if (iov->niov != 1) { >> +buf = g_try_malloc(bytes); >> +if (bytes && buf == NULL) { >> +return -ENOMEM; >> +} >> +qemu_iovec_to_buf(iov, 0, buf, bytes); >> +my_buffer = true; >> +} else { >> +buf = iov->iov[0].iov_base; If we took the else branch, then we definitely do not want to be calling g_free(buf). >> } >> >> -qemu_iovec_to_buf(iov, 0, buf, bytes); >> - >> if (nfs_pwrite_async(client->context, client->fh, >> offset, bytes, buf, >> nfs_co_generic_cb, &task) != 0) { >> -g_free(buf); >> +if (my_buffer) { >> +g_free(buf); >> +} It looks correct as-is to me. -- Eric Blake eblake redhat com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
Re: [Qemu-devel] [PATCH 2/2] block/nfs: try to avoid the bounce buffer in pwritev
On Fri, Feb 17, 2017 at 05:39:01PM +0100, Peter Lieven wrote: > if the passed qiov contains exactly one iov we can > pass the buffer directly. > > Signed-off-by: Peter Lieven > --- > block/nfs.c | 23 --- > 1 file changed, 16 insertions(+), 7 deletions(-) > > diff --git a/block/nfs.c b/block/nfs.c > index ab5dcc2..bb4b75f 100644 > --- a/block/nfs.c > +++ b/block/nfs.c > @@ -295,20 +295,27 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState > *bs, uint64_t offset, > NFSClient *client = bs->opaque; > NFSRPC task; > char *buf = NULL; > +bool my_buffer = false; g_free() is a nop if buf is NULL, so there is no need for the my_buffer variable & check. > > nfs_co_init_task(bs, &task); > > -buf = g_try_malloc(bytes); > -if (bytes && buf == NULL) { > -return -ENOMEM; > +if (iov->niov != 1) { > +buf = g_try_malloc(bytes); > +if (bytes && buf == NULL) { > +return -ENOMEM; > +} > +qemu_iovec_to_buf(iov, 0, buf, bytes); > +my_buffer = true; > +} else { > +buf = iov->iov[0].iov_base; > } > > -qemu_iovec_to_buf(iov, 0, buf, bytes); > - > if (nfs_pwrite_async(client->context, client->fh, > offset, bytes, buf, > nfs_co_generic_cb, &task) != 0) { > -g_free(buf); > +if (my_buffer) { > +g_free(buf); > +} > return -ENOMEM; > } > > @@ -317,7 +324,9 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState > *bs, uint64_t offset, > qemu_coroutine_yield(); > } > > -g_free(buf); > +if (my_buffer) { > +g_free(buf); > +} > > if (task.ret != bytes) { > return task.ret < 0 ? task.ret : -EIO; > -- > 1.9.1 >