| Message ID | 1466598927-5990-1-git-send-email-den@openvz.org |
|---|---|
| State | New |
| Headers | show |
On 06/22/2016 03:35 PM, Denis V. Lunev wrote: > There are 2 deficiencies here: > - mirror_iteration could start several requests inside. Thus we could > simply have more in_flight requests than MAX_IN_FLIGHT. > - keeping this in mind throttling in mirror_run which is checking > s->in_flight == MAX_IN_FLIGHT is wrong. > > The patch adds the check and throttling into mirror_iteration and fixes > the check in mirror_run() to be sure. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Jeff Cody <jcody@redhat.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Max Reitz <mreitz@redhat.com> > --- > block/mirror.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/mirror.c b/block/mirror.c > index a04ed9c..e881ef6 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -399,6 +399,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > } > } > > + while (s->in_flight >= MAX_IN_FLIGHT) { > + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); > + mirror_wait_for_io(s); > + } > + > mirror_clip_sectors(s, sector_num, &io_sectors); > switch (mirror_method) { > case MIRROR_METHOD_COPY: > @@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque) > */ > if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && > s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { > - if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || > + if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || > (cnt == 0 && s->in_flight > 0)) { > trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); > mirror_wait_for_io(s); ping
On 22.06.2016 14:35, Denis V. Lunev wrote: > There are 2 deficiencies here: > - mirror_iteration could start several requests inside. Thus we could > simply have more in_flight requests than MAX_IN_FLIGHT. > - keeping this in mind throttling in mirror_run which is checking > s->in_flight == MAX_IN_FLIGHT is wrong. > > The patch adds the check and throttling into mirror_iteration and fixes > the check in mirror_run() to be sure. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Jeff Cody <jcody@redhat.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Max Reitz <mreitz@redhat.com> > --- > block/mirror.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/mirror.c b/block/mirror.c > index a04ed9c..e881ef6 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -399,6 +399,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > } > } > > + while (s->in_flight >= MAX_IN_FLIGHT) { > + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); > + mirror_wait_for_io(s); > + } > + > mirror_clip_sectors(s, sector_num, &io_sectors); > switch (mirror_method) { > case MIRROR_METHOD_COPY: > @@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque) > */ > if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && > s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { > - if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || > + if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || > (cnt == 0 && s->in_flight > 0)) { > trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); > mirror_wait_for_io(s); > Using >= seems fine to me, but with the first hunk applied I can't imagine how s->in_flight should grow beyond MAX_IN_FLIGHT. Don't get me wrong, I myself like to use >= even where the > case should never happen, I'm just wondering if I'm missing something here. Reviewed-by: Max Reitz <mreitz@redhat.com>
On 06/29/2016 07:08 PM, Max Reitz wrote: > On 22.06.2016 14:35, Denis V. Lunev wrote: >> There are 2 deficiencies here: >> - mirror_iteration could start several requests inside. Thus we could >> simply have more in_flight requests than MAX_IN_FLIGHT. >> - keeping this in mind throttling in mirror_run which is checking >> s->in_flight == MAX_IN_FLIGHT is wrong. >> >> The patch adds the check and throttling into mirror_iteration and fixes >> the check in mirror_run() to be sure. >> >> Signed-off-by: Denis V. Lunev <den@openvz.org> >> CC: Jeff Cody <jcody@redhat.com> >> CC: Kevin Wolf <kwolf@redhat.com> >> CC: Max Reitz <mreitz@redhat.com> >> --- >> block/mirror.c | 7 ++++++- >> 1 file changed, 6 insertions(+), 1 deletion(-) >> >> diff --git a/block/mirror.c b/block/mirror.c >> index a04ed9c..e881ef6 100644 >> --- a/block/mirror.c >> +++ b/block/mirror.c >> @@ -399,6 +399,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) >> } >> } >> >> + while (s->in_flight >= MAX_IN_FLIGHT) { >> + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); >> + mirror_wait_for_io(s); >> + } >> + >> mirror_clip_sectors(s, sector_num, &io_sectors); >> switch (mirror_method) { >> case MIRROR_METHOD_COPY: >> @@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque) >> */ >> if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && >> s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { >> - if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || >> + if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || >> (cnt == 0 && s->in_flight > 0)) { >> trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); >> mirror_wait_for_io(s); >> > Using >= seems fine to me, but with the first hunk applied I can't > imagine how s->in_flight should grow beyond MAX_IN_FLIGHT. Don't get me > wrong, I myself like to use >= even where the > case should never > happen, I'm just wondering if I'm missing something here. > > Reviewed-by: Max Reitz <mreitz@redhat.com> > I think that this should not happen anymore, but I'd like to stay on the safe side. Den
On Wed, Jun 22, 2016 at 03:35:27PM +0300, Denis V. Lunev wrote: > There are 2 deficiencies here: > - mirror_iteration could start several requests inside. Thus we could > simply have more in_flight requests than MAX_IN_FLIGHT. > - keeping this in mind throttling in mirror_run which is checking > s->in_flight == MAX_IN_FLIGHT is wrong. > > The patch adds the check and throttling into mirror_iteration and fixes > the check in mirror_run() to be sure. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Jeff Cody <jcody@redhat.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Max Reitz <mreitz@redhat.com> > --- > block/mirror.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/mirror.c b/block/mirror.c > index a04ed9c..e881ef6 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -399,6 +399,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > } > } > > + while (s->in_flight >= MAX_IN_FLIGHT) { > + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); > + mirror_wait_for_io(s); > + } > + > mirror_clip_sectors(s, sector_num, &io_sectors); > switch (mirror_method) { > case MIRROR_METHOD_COPY: > @@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque) > */ > if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && > s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { > - if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || > + if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || > (cnt == 0 && s->in_flight > 0)) { > trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); > mirror_wait_for_io(s); > -- > 2.1.4 > Reviewed-by: Jeff Cody <jcody@redhat.com>
On Wed, Jun 22, 2016 at 03:35:27PM +0300, Denis V. Lunev wrote: > There are 2 deficiencies here: > - mirror_iteration could start several requests inside. Thus we could > simply have more in_flight requests than MAX_IN_FLIGHT. > - keeping this in mind throttling in mirror_run which is checking > s->in_flight == MAX_IN_FLIGHT is wrong. > > The patch adds the check and throttling into mirror_iteration and fixes > the check in mirror_run() to be sure. > > Signed-off-by: Denis V. Lunev <den@openvz.org> > CC: Jeff Cody <jcody@redhat.com> > CC: Kevin Wolf <kwolf@redhat.com> > CC: Max Reitz <mreitz@redhat.com> > --- > block/mirror.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/block/mirror.c b/block/mirror.c > index a04ed9c..e881ef6 100644 > --- a/block/mirror.c > +++ b/block/mirror.c > @@ -399,6 +399,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) > } > } > > + while (s->in_flight >= MAX_IN_FLIGHT) { > + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); > + mirror_wait_for_io(s); > + } > + > mirror_clip_sectors(s, sector_num, &io_sectors); > switch (mirror_method) { > case MIRROR_METHOD_COPY: > @@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque) > */ > if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && > s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { > - if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || > + if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || > (cnt == 0 && s->in_flight > 0)) { > trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); > mirror_wait_for_io(s); > -- > 2.1.4 > Thanks, Applied to my block branch: git://github.com/codyprime/qemu-kvm-jtc.git block -Jeff
diff --git a/block/mirror.c b/block/mirror.c index a04ed9c..e881ef6 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -399,6 +399,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) } } + while (s->in_flight >= MAX_IN_FLIGHT) { + trace_mirror_yield_in_flight(s, sector_num, s->in_flight); + mirror_wait_for_io(s); + } + mirror_clip_sectors(s, sector_num, &io_sectors); switch (mirror_method) { case MIRROR_METHOD_COPY: @@ -634,7 +639,7 @@ static void coroutine_fn mirror_run(void *opaque) */ if (qemu_clock_get_ns(QEMU_CLOCK_REALTIME) - last_pause_ns < SLICE_TIME && s->common.iostatus == BLOCK_DEVICE_IO_STATUS_OK) { - if (s->in_flight == MAX_IN_FLIGHT || s->buf_free_count == 0 || + if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || (cnt == 0 && s->in_flight > 0)) { trace_mirror_yield(s, s->in_flight, s->buf_free_count, cnt); mirror_wait_for_io(s);
There are 2 deficiencies here: - mirror_iteration could start several requests inside. Thus we could simply have more in_flight requests than MAX_IN_FLIGHT. - keeping this in mind throttling in mirror_run which is checking s->in_flight == MAX_IN_FLIGHT is wrong. The patch adds the check and throttling into mirror_iteration and fixes the check in mirror_run() to be sure. Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Jeff Cody <jcody@redhat.com> CC: Kevin Wolf <kwolf@redhat.com> CC: Max Reitz <mreitz@redhat.com> --- block/mirror.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)