search for: local_clock

...- Disable"); > > @@ -287,12 +289,23 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static bool tx_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + unsigned long now = local_clock() >> 10; local_clock might go backwards if we jump between CPUs. One way to fix would be to record the CPU id and break out of loop if that changes. Also - defer this until we actually know we need it? > + > + return busyloop_timeout && !need_resched() && > +...

...- Disable"); > > @@ -287,12 +289,23 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static bool tx_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + unsigned long now = local_clock() >> 10; local_clock might go backwards if we jump between CPUs. One way to fix would be to record the CPU id and break out of loop if that changes. Also - defer this until we actually know we need it? > + > + return busyloop_timeout && !need_resched() && > +...

This path introduces a helper which can give a hint for whether or not there's a work queued in the work list. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/vhost/vhost.c | 6 ++++++ drivers/vhost/vhost.h | 1 + 2 files changed, 7 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index eec2f11..d42d11e 100644 --- a/drivers/vhost/vhost.c +++

This path introduces a helper which can give a hint for whether or not there's a work queued in the work list. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/vhost/vhost.c | 6 ++++++ drivers/vhost/vhost.h | 1 + 2 files changed, 7 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index eec2f11..d42d11e 100644 --- a/drivers/vhost/vhost.c +++

...; @@ -287,12 +289,23 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) >> rcu_read_unlock_bh(); >> } >> >> +static bool tx_can_busy_poll(struct vhost_dev *dev, >> + unsigned long endtime) >> +{ >> + unsigned long now = local_clock() >> 10; > local_clock might go backwards if we jump between CPUs. > One way to fix would be to record the CPU id and break > out of loop if that changes. Right, or maybe disable preemption in this case? > > Also - defer this until we actually know we need it? Right. > &...

..." 1 -Enable; 0 - Disable"); @@ -287,12 +289,23 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) rcu_read_unlock_bh(); } +static bool tx_can_busy_poll(struct vhost_dev *dev, + unsigned long endtime) +{ + unsigned long now = local_clock() >> 10; + + return busyloop_timeout && !need_resched() && + !time_after(now, endtime) && !vhost_has_work(dev) && + single_task_running(); +} + /* Expects to be always run from workqueue - which acts as * read-size critical section for our kind...

...a69e..c91af93 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -287,6 +287,44 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static inline unsigned long busy_clock(void) > +{ > + return local_clock() >> 10; > +} > + > +static bool vhost_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + return likely(!need_resched()) && > + likely(!time_after(busy_clock(), endtime)) && > + likely(!signal_pending(current)) &am...

...a69e..c91af93 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -287,6 +287,44 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static inline unsigned long busy_clock(void) > +{ > + return local_clock() >> 10; > +} > + > +static bool vhost_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + return likely(!need_resched()) && > + likely(!time_after(busy_clock(), endtime)) && > + likely(!signal_pending(current)) &am...

...da69e..c91af93 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -287,6 +287,44 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static inline unsigned long busy_clock(void) > +{ > + return local_clock() >> 10; > +} > + > +static bool vhost_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + return likely(!need_resched()) && > + likely(!time_after(busy_clock(), endtime)) && > + likely(!signal_pending(current)) &am...

...da69e..c91af93 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -287,6 +287,44 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static inline unsigned long busy_clock(void) > +{ > + return local_clock() >> 10; > +} > + > +static bool vhost_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + return likely(!need_resched()) && > + likely(!time_after(busy_clock(), endtime)) && > + likely(!signal_pending(current)) &am...

...a69e..ce6da77 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -287,6 +287,41 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static inline unsigned long busy_clock(void) > +{ > + return local_clock() >> 10; > +} > + > +static bool vhost_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + return likely(!need_resched()) && > + likely(!time_after(busy_clock(), endtime)) && > + likely(!signal_pending(current)) &am...

...a69e..ce6da77 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -287,6 +287,41 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > rcu_read_unlock_bh(); > } > > +static inline unsigned long busy_clock(void) > +{ > + return local_clock() >> 10; > +} > + > +static bool vhost_can_busy_poll(struct vhost_dev *dev, > + unsigned long endtime) > +{ > + return likely(!need_resched()) && > + likely(!time_after(busy_clock(), endtime)) && > + likely(!signal_pending(current)) &am...

...+++ b/drivers/vhost/net.c > >>@@ -287,6 +287,41 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > >> rcu_read_unlock_bh(); > >> } > >> > >>+static inline unsigned long busy_clock(void) > >>+{ > >>+ return local_clock() >> 10; > >>+} > >>+ > >>+static bool vhost_can_busy_poll(struct vhost_dev *dev, > >>+ unsigned long endtime) > >>+{ > >>+ return likely(!need_resched()) && > >>+ likely(!time_after(busy_clock(), endtime)) &...

...+++ b/drivers/vhost/net.c > >>@@ -287,6 +287,41 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) > >> rcu_read_unlock_bh(); > >> } > >> > >>+static inline unsigned long busy_clock(void) > >>+{ > >>+ return local_clock() >> 10; > >>+} > >>+ > >>+static bool vhost_can_busy_poll(struct vhost_dev *dev, > >>+ unsigned long endtime) > >>+{ > >>+ return likely(!need_resched()) && > >>+ likely(!time_after(busy_clock(), endtime)) &...

...hcd_map_urb_for_dma+0x5f8/0x780 [<ffffffff81108d8d>] ? trace_hardirqs_on+0xd/0x10 [<ffffffff8162469d>] usb_hcd_submit_urb+0x1cd/0xac0 [<ffffffff810e82ca>] ? sched_clock_cpu+0x8a/0xb0 [<ffffffff816e6387>] ? led_trigger_blink_oneshot+0x77/0x90 [<ffffffff810e8345>] ? local_clock+0x15/0x20 [<ffffffff81127b6d>] ? debug_lockdep_rcu_enabled+0x1d/0x20 [<ffffffff8162626c>] usb_submit_urb+0x3fc/0x5a0 [<ffffffff8187fb17>] ? _raw_read_unlock+0x27/0x40 [<ffffffffa04e548d>] intr_complete+0x3d/0xd0 [usbnet] [<ffffffff81622bbe>] __usb_hcd_giveback_urb...

...drivers/vhost/net.c >> > @@ -287,6 +287,44 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) >> > rcu_read_unlock_bh(); >> > } >> > >> > +static inline unsigned long busy_clock(void) >> > +{ >> > + return local_clock() >> 10; >> > +} >> > + >> > +static bool vhost_can_busy_poll(struct vhost_dev *dev, >> > + unsigned long endtime) >> > +{ >> > + return likely(!need_resched()) && >> > + likely(!time_after(busy_clock(), endtime)...

...node_need_killpriv+0x2d/0x37 [ 1998.478275] [<ffffffff810d8309>] file_remove_suid+0x27/0x64 [ 1998.478275] [<ffffffffa0240e14>] btrfs_file_aio_write+0x159/0x49a [btrfs] [ 1998.478275] [<ffffffff8107bfd2>] ? trace_hardirqs_off+0xd/0xf [ 1998.478275] [<ffffffff81071f42>] ? local_clock+0x36/0x4d [ 1998.478275] [<ffffffff810800ab>] ? lock_release_non_nested+0xdb/0x263 [ 1998.478275] [<ffffffff81121996>] do_sync_write+0xcb/0x108 [ 1998.478275] [<ffffffff810f33a4>] ? might_fault+0x5c/0xac [ 1998.478275] [<ffffffff8107ed01>] ? lock_is_held+0x8d/0x98 [ 1998...

...ce+0x364/0x3e0 [ 37.497413] [<c0b91445>] ? do_init_module+0x21/0x1b7 [ 37.497413] [<c0b91445>] ? do_init_module+0x21/0x1b7 [ 37.497413] [<c0b91474>] do_init_module+0x50/0x1b7 [ 37.497413] [<c050909c>] load_module+0x1ebc/0x2550 [ 37.497413] [<c049ad43>] ? local_clock+0x13/0x20 [ 37.497413] [<c0509877>] SyS_init_module+0x147/0x1a0 [ 37.497413] [<c04be63c>] ? trace_hardirqs_on_caller+0x12c/0x1d0 [ 37.497413] [<c052711c>] ? __audit_syscall_entry+0x8c/0xe0 [ 37.497413] [<c0b9ad2f>] sysenter_do_call+0x12/0x12 [ 37.497413] ---[ e...

This series tries to add basic busy polling for vhost net. The idea is simple: at the end of tx/rx processing, busy polling for new tx added descriptor and rx receive socket for a while. The maximum number of time (in us) could be spent on busy polling was specified ioctl. Test A were done through: - 50 us as busy loop timeout - Netperf 2.6 - Two machines with back to back connected mlx4 - Guest

This series tries to add basic busy polling for vhost net. The idea is simple: at the end of tx/rx processing, busy polling for new tx added descriptor and rx receive socket for a while. The maximum number of time (in us) could be spent on busy polling was specified ioctl. Test A were done through: - 50 us as busy loop timeout - Netperf 2.6 - Two machines with back to back connected mlx4 - Guest