Wei Liu
2013-Oct-27 11:11 UTC
[PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
time_after_eq() only works if the delta is < MAX_ULONG/2.
For a 32bit Dom0, if netfront sends packets at a very low rate, the time
between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2
and the test for timer_after_eq() will be incorrect. Credit will not be
replenished and the guest may become unable to send packets (e.g., if
prior to the long gap, all credit was exhausted).
Use jiffies_64 variant to mitigate this problem for 32bit Dom0.
Suggested-by: Jan Beulich <jbeulich@suse.com>
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Jason Luan <jianhai.luan@oracle.com>
---
drivers/net/xen-netback/common.h | 1 +
drivers/net/xen-netback/interface.c | 4 ++--
drivers/net/xen-netback/netback.c | 13 ++++++-------
3 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 5715318..400fea1 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -163,6 +163,7 @@ struct xenvif {
unsigned long credit_usec;
unsigned long remaining_credit;
struct timer_list credit_timeout;
+ u64 credit_window_start;
/* Statistics */
unsigned long rx_gso_checksum_fixup;
diff --git a/drivers/net/xen-netback/interface.c
b/drivers/net/xen-netback/interface.c
index 01bb854..8c45b63 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -312,8 +312,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t
domid,
vif->credit_bytes = vif->remaining_credit = ~0UL;
vif->credit_usec = 0UL;
init_timer(&vif->credit_timeout);
- /* Initialize ''expires'' now: it''s used to track the
credit window. */
- vif->credit_timeout.expires = jiffies;
+ /* credit window is tracked in credit_window_start */
+ vif->credit_window_start = get_jiffies_64();
dev->netdev_ops = &xenvif_netdev_ops;
dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO;
diff --git a/drivers/net/xen-netback/netback.c
b/drivers/net/xen-netback/netback.c
index f3e591c..1bc0688 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1185,18 +1185,17 @@ out:
static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
{
- unsigned long now = jiffies;
- unsigned long next_credit - vif->credit_timeout.expires +
- msecs_to_jiffies(vif->credit_usec / 1000);
+ u64 now = get_jiffies_64();
+ u64 next_credit = vif->credit_window_start +
+ (u64)msecs_to_jiffies(vif->credit_usec / 1000);
/* Timer could already be pending in rare cases. */
if (timer_pending(&vif->credit_timeout))
return true;
/* Passed the point where we can replenish credit? */
- if (time_after_eq(now, next_credit)) {
- vif->credit_timeout.expires = now;
+ if (time_after_eq64(now, next_credit)) {
+ vif->credit_timeout.expires = (unsigned long)now;
tx_add_credit(vif);
}
@@ -1207,7 +1206,7 @@ static bool tx_credit_exceeded(struct xenvif *vif,
unsigned size)
vif->credit_timeout.function tx_credit_callback;
mod_timer(&vif->credit_timeout,
- next_credit);
+ (unsigned long)next_credit);
return true;
}
--
1.7.10.4
annie li
2013-Oct-28 02:36 UTC
Re: [PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
On 2013-10-27 19:11, Wei Liu wrote:> time_after_eq() only works if the delta is < MAX_ULONG/2. > > For a 32bit Dom0, if netfront sends packets at a very low rate, the time > between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2 > and the test for timer_after_eq() will be incorrect. Credit will not be > replenished and the guest may become unable to send packets (e.g., if > prior to the long gap, all credit was exhausted). > > Use jiffies_64 variant to mitigate this problem for 32bit Dom0. > > Suggested-by: Jan Beulich <jbeulich@suse.com> > Suggested-by: David Vrabel <david.vrabel@citrix.com> > Signed-off-by: Wei Liu <wei.liu2@citrix.com> > Cc: Ian Campbell <ian.campbell@citrix.com> > Cc: Jason Luan <jianhai.luan@oracle.com> > --- > drivers/net/xen-netback/common.h | 1 + > drivers/net/xen-netback/interface.c | 4 ++-- > drivers/net/xen-netback/netback.c | 13 ++++++------- > 3 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h > index 5715318..400fea1 100644 > --- a/drivers/net/xen-netback/common.h > +++ b/drivers/net/xen-netback/common.h > @@ -163,6 +163,7 @@ struct xenvif { > unsigned long credit_usec; > unsigned long remaining_credit; > struct timer_list credit_timeout; > + u64 credit_window_start; > > /* Statistics */ > unsigned long rx_gso_checksum_fixup; > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c > index 01bb854..8c45b63 100644 > --- a/drivers/net/xen-netback/interface.c > +++ b/drivers/net/xen-netback/interface.c > @@ -312,8 +312,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, > vif->credit_bytes = vif->remaining_credit = ~0UL; > vif->credit_usec = 0UL; > init_timer(&vif->credit_timeout); > - /* Initialize ''expires'' now: it''s used to track the credit window. */ > - vif->credit_timeout.expires = jiffies; > + /* credit window is tracked in credit_window_start */ > + vif->credit_window_start = get_jiffies_64(); > > dev->netdev_ops = &xenvif_netdev_ops; > dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO; > diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c > index f3e591c..1bc0688 100644 > --- a/drivers/net/xen-netback/netback.c > +++ b/drivers/net/xen-netback/netback.c > @@ -1185,18 +1185,17 @@ out: > > static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) > { > - unsigned long now = jiffies; > - unsigned long next_credit > - vif->credit_timeout.expires + > - msecs_to_jiffies(vif->credit_usec / 1000); > + u64 now = get_jiffies_64(); > + u64 next_credit = vif->credit_window_start + > + (u64)msecs_to_jiffies(vif->credit_usec / 1000);You simply replace "credit_timeout.expires" with "vif->credit_window_start" here, and never update "vif->credit_window_start" in following code.> > /* Timer could already be pending in rare cases. */ > if (timer_pending(&vif->credit_timeout)) > return true; > > /* Passed the point where we can replenish credit? */ > - if (time_after_eq(now, next_credit)) { > - vif->credit_timeout.expires = now; > + if (time_after_eq64(now, next_credit)) { > + vif->credit_timeout.expires = (unsigned long)now;updates credit_window_start as following, vif->credit_window_start = (unsigned long)now;> tx_add_credit(vif); > } > > @@ -1207,7 +1206,7 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) > vif->credit_timeout.function > tx_credit_callback; > mod_timer(&vif->credit_timeout, > - next_credit); > + (unsigned long)next_credit);vif->credit_timeout.expires is unsigned long, and this still causes original issue on 32bit system, which works well on 64bit. Or rewriting code to avoid uses of vif->credit_timeout.expires, but it is complex. BTW, I prefer Luan''s patch which is simple and clear. Thanks Annie
annie li
2013-Oct-28 02:58 UTC
Re: [PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
On 2013-10-28 10:36, annie li wrote:> > On 2013-10-27 19:11, Wei Liu wrote: >> time_after_eq() only works if the delta is < MAX_ULONG/2. >> >> For a 32bit Dom0, if netfront sends packets at a very low rate, the time >> between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2 >> and the test for timer_after_eq() will be incorrect. Credit will not be >> replenished and the guest may become unable to send packets (e.g., if >> prior to the long gap, all credit was exhausted). >> >> Use jiffies_64 variant to mitigate this problem for 32bit Dom0. >> >> Suggested-by: Jan Beulich <jbeulich@suse.com> >> Suggested-by: David Vrabel <david.vrabel@citrix.com> >> Signed-off-by: Wei Liu <wei.liu2@citrix.com> >> Cc: Ian Campbell <ian.campbell@citrix.com> >> Cc: Jason Luan <jianhai.luan@oracle.com> >> --- >> drivers/net/xen-netback/common.h | 1 + >> drivers/net/xen-netback/interface.c | 4 ++-- >> drivers/net/xen-netback/netback.c | 13 ++++++------- >> 3 files changed, 9 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/net/xen-netback/common.h >> b/drivers/net/xen-netback/common.h >> index 5715318..400fea1 100644 >> --- a/drivers/net/xen-netback/common.h >> +++ b/drivers/net/xen-netback/common.h >> @@ -163,6 +163,7 @@ struct xenvif { >> unsigned long credit_usec; >> unsigned long remaining_credit; >> struct timer_list credit_timeout; >> + u64 credit_window_start; >> /* Statistics */ >> unsigned long rx_gso_checksum_fixup; >> diff --git a/drivers/net/xen-netback/interface.c >> b/drivers/net/xen-netback/interface.c >> index 01bb854..8c45b63 100644 >> --- a/drivers/net/xen-netback/interface.c >> +++ b/drivers/net/xen-netback/interface.c >> @@ -312,8 +312,8 @@ struct xenvif *xenvif_alloc(struct device >> *parent, domid_t domid, >> vif->credit_bytes = vif->remaining_credit = ~0UL; >> vif->credit_usec = 0UL; >> init_timer(&vif->credit_timeout); >> - /* Initialize ''expires'' now: it''s used to track the credit >> window. */ >> - vif->credit_timeout.expires = jiffies; >> + /* credit window is tracked in credit_window_start */ >> + vif->credit_window_start = get_jiffies_64(); >> dev->netdev_ops = &xenvif_netdev_ops; >> dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO; >> diff --git a/drivers/net/xen-netback/netback.c >> b/drivers/net/xen-netback/netback.c >> index f3e591c..1bc0688 100644 >> --- a/drivers/net/xen-netback/netback.c >> +++ b/drivers/net/xen-netback/netback.c >> @@ -1185,18 +1185,17 @@ out: >> static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) >> { >> - unsigned long now = jiffies; >> - unsigned long next_credit >> - vif->credit_timeout.expires + >> - msecs_to_jiffies(vif->credit_usec / 1000); >> + u64 now = get_jiffies_64(); >> + u64 next_credit = vif->credit_window_start + >> + (u64)msecs_to_jiffies(vif->credit_usec / 1000); > > You simply replace "credit_timeout.expires" with > "vif->credit_window_start" here, and never update > "vif->credit_window_start" in following code. > >> /* Timer could already be pending in rare cases. */ >> if (timer_pending(&vif->credit_timeout)) >> return true; >> /* Passed the point where we can replenish credit? */ >> - if (time_after_eq(now, next_credit)) { >> - vif->credit_timeout.expires = now; >> + if (time_after_eq64(now, next_credit)) { >> + vif->credit_timeout.expires = (unsigned long)now; > > updates credit_window_start as following, > vif->credit_window_start = (unsigned long)now;both credit_window_start and credit_timeout.expires need to be updated here, vif->credit_window_start = (unsigned long)now; vif->credit_timeout.expires = (unsigned long)now;> >> tx_add_credit(vif); >> } >> @@ -1207,7 +1206,7 @@ static bool tx_credit_exceeded(struct xenvif >> *vif, unsigned size) >> vif->credit_timeout.function >> tx_credit_callback; >> mod_timer(&vif->credit_timeout, >> - next_credit); >> + (unsigned long)next_credit); > > vif->credit_timeout.expires is unsigned long, and this still causes > original issue on 32bit system, which works well on 64bit. Or > rewriting code to avoid uses of vif->credit_timeout.expires, but it is > complex.My understanding here is wrong, please ignore this. Thanks Annie
jianhai luan
2013-Oct-28 06:28 UTC
Re: [PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
On 2013-10-28 10:58, annie li wrote:> > On 2013-10-28 10:36, annie li wrote: >> >> On 2013-10-27 19:11, Wei Liu wrote: >>> time_after_eq() only works if the delta is < MAX_ULONG/2. >>> >>> For a 32bit Dom0, if netfront sends packets at a very low rate, the >>> time >>> between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2 >>> and the test for timer_after_eq() will be incorrect. Credit will not be >>> replenished and the guest may become unable to send packets (e.g., if >>> prior to the long gap, all credit was exhausted). >>> >>> Use jiffies_64 variant to mitigate this problem for 32bit Dom0. >>> >>> Suggested-by: Jan Beulich <jbeulich@suse.com> >>> Suggested-by: David Vrabel <david.vrabel@citrix.com> >>> Signed-off-by: Wei Liu <wei.liu2@citrix.com> >>> Cc: Ian Campbell <ian.campbell@citrix.com> >>> Cc: Jason Luan <jianhai.luan@oracle.com> >>> --- >>> drivers/net/xen-netback/common.h | 1 + >>> drivers/net/xen-netback/interface.c | 4 ++-- >>> drivers/net/xen-netback/netback.c | 13 ++++++------- >>> 3 files changed, 9 insertions(+), 9 deletions(-) >>> >>> diff --git a/drivers/net/xen-netback/common.h >>> b/drivers/net/xen-netback/common.h >>> index 5715318..400fea1 100644 >>> --- a/drivers/net/xen-netback/common.h >>> +++ b/drivers/net/xen-netback/common.h >>> @@ -163,6 +163,7 @@ struct xenvif { >>> unsigned long credit_usec; >>> unsigned long remaining_credit; >>> struct timer_list credit_timeout; >>> + u64 credit_window_start; >>> /* Statistics */ >>> unsigned long rx_gso_checksum_fixup; >>> diff --git a/drivers/net/xen-netback/interface.c >>> b/drivers/net/xen-netback/interface.c >>> index 01bb854..8c45b63 100644 >>> --- a/drivers/net/xen-netback/interface.c >>> +++ b/drivers/net/xen-netback/interface.c >>> @@ -312,8 +312,8 @@ struct xenvif *xenvif_alloc(struct device >>> *parent, domid_t domid, >>> vif->credit_bytes = vif->remaining_credit = ~0UL; >>> vif->credit_usec = 0UL; >>> init_timer(&vif->credit_timeout); >>> - /* Initialize ''expires'' now: it''s used to track the credit >>> window. */ >>> - vif->credit_timeout.expires = jiffies; >>> + /* credit window is tracked in credit_window_start */ >>> + vif->credit_window_start = get_jiffies_64(); >>> dev->netdev_ops = &xenvif_netdev_ops; >>> dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO; >>> diff --git a/drivers/net/xen-netback/netback.c >>> b/drivers/net/xen-netback/netback.c >>> index f3e591c..1bc0688 100644 >>> --- a/drivers/net/xen-netback/netback.c >>> +++ b/drivers/net/xen-netback/netback.c >>> @@ -1185,18 +1185,17 @@ out: >>> static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) >>> { >>> - unsigned long now = jiffies; >>> - unsigned long next_credit >>> - vif->credit_timeout.expires + >>> - msecs_to_jiffies(vif->credit_usec / 1000); >>> + u64 now = get_jiffies_64(); >>> + u64 next_credit = vif->credit_window_start + >>> + (u64)msecs_to_jiffies(vif->credit_usec / 1000); >> >> You simply replace "credit_timeout.expires" with >> "vif->credit_window_start" here, and never update >> "vif->credit_window_start" in following code. >> >>> /* Timer could already be pending in rare cases. */ >>> if (timer_pending(&vif->credit_timeout)) >>> return true; >>> /* Passed the point where we can replenish credit? */ >>> - if (time_after_eq(now, next_credit)) { >>> - vif->credit_timeout.expires = now; >>> + if (time_after_eq64(now, next_credit)) { >>> + vif->credit_timeout.expires = (unsigned long)now; >> >> updates credit_window_start as following, >> vif->credit_window_start = (unsigned long)now; > > both credit_window_start and credit_timeout.expires need to be updated > here, > > vif->credit_window_start = (unsigned long)now; > vif->credit_timeout.expires = (unsigned long)now;Annie should be correct. It is good to me but i afraid that get_jiffies_64() and time_after_eq64() will bring some performance''s load when transmit is busy in 32bit. I will do some test about the patch. No matter what, i prefer own patch. Thanks, Jason> >> >>> tx_add_credit(vif); >>> } >>> @@ -1207,7 +1206,7 @@ static bool tx_credit_exceeded(struct xenvif >>> *vif, unsigned size) >>> vif->credit_timeout.function >>> tx_credit_callback; >>> mod_timer(&vif->credit_timeout, >>> - next_credit); >>> + (unsigned long)next_credit); >> >> vif->credit_timeout.expires is unsigned long, and this still causes >> original issue on 32bit system, which works well on 64bit. Or >> rewriting code to avoid uses of vif->credit_timeout.expires, but it >> is complex. > My understanding here is wrong, please ignore this. > > Thanks > Annie
David Vrabel
2013-Oct-28 08:21 UTC
Re: [PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
On 27/10/2013 11:11, Wei Liu wrote:> time_after_eq() only works if the delta is < MAX_ULONG/2. > > For a 32bit Dom0, if netfront sends packets at a very low rate, the time > between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2 > and the test for timer_after_eq() will be incorrect. Credit will not be > replenished and the guest may become unable to send packets (e.g., if > prior to the long gap, all credit was exhausted). > > Use jiffies_64 variant to mitigate this problem for 32bit Dom0.Thanks.> Suggested-by: Jan Beulich <jbeulich@suse.com> > Suggested-by: David Vrabel <david.vrabel@citrix.com>Jan''s suggestion; I just agreed with him.> Signed-off-by: Wei Liu <wei.liu2@citrix.com> > Cc: Ian Campbell <ian.campbell@citrix.com> > Cc: Jason Luan <jianhai.luan@oracle.com> > --- > drivers/net/xen-netback/common.h | 1 + > drivers/net/xen-netback/interface.c | 4 ++-- > drivers/net/xen-netback/netback.c | 13 ++++++------- > 3 files changed, 9 insertions(+), 9 deletions(-) > > diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h > index 5715318..400fea1 100644 > --- a/drivers/net/xen-netback/common.h > +++ b/drivers/net/xen-netback/common.h > @@ -163,6 +163,7 @@ struct xenvif { > unsigned long credit_usec; > unsigned long remaining_credit; > struct timer_list credit_timeout; > + u64 credit_window_start; > > /* Statistics */ > unsigned long rx_gso_checksum_fixup; > diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c > index 01bb854..8c45b63 100644 > --- a/drivers/net/xen-netback/interface.c > +++ b/drivers/net/xen-netback/interface.c > @@ -312,8 +312,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, > vif->credit_bytes = vif->remaining_credit = ~0UL; > vif->credit_usec = 0UL; > init_timer(&vif->credit_timeout); > - /* Initialize ''expires'' now: it''s used to track the credit window. */ > - vif->credit_timeout.expires = jiffies; > + /* credit window is tracked in credit_window_start */You could drop this comment as the field name makes this obvious.> + vif->credit_window_start = get_jiffies_64(); > > dev->netdev_ops = &xenvif_netdev_ops; > dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO; > diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c > index f3e591c..1bc0688 100644 > --- a/drivers/net/xen-netback/netback.c > +++ b/drivers/net/xen-netback/netback.c > @@ -1185,18 +1185,17 @@ out: > > static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) > { > - unsigned long now = jiffies; > - unsigned long next_credit > - vif->credit_timeout.expires + > - msecs_to_jiffies(vif->credit_usec / 1000); > + u64 now = get_jiffies_64(); > + u64 next_credit = vif->credit_window_start + > + (u64)msecs_to_jiffies(vif->credit_usec / 1000); > > /* Timer could already be pending in rare cases. */ > if (timer_pending(&vif->credit_timeout)) > return true; > > /* Passed the point where we can replenish credit? */ > - if (time_after_eq(now, next_credit)) { > - vif->credit_timeout.expires = now; > + if (time_after_eq64(now, next_credit)) { > + vif->credit_timeout.expires = (unsigned long)now;Need to set vif->credit_window_start = now here instead of .expires.> tx_add_credit(vif); > } > > @@ -1207,7 +1206,7 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) > vif->credit_timeout.function > tx_credit_callback; > mod_timer(&vif->credit_timeout, > - next_credit); > + (unsigned long)next_credit);Need to set vif->credit_window_start = next_credit here as well. David
jianhai luan
2013-Oct-28 08:36 UTC
Re: [PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
On 2013-10-28 16:21, David Vrabel wrote:> On 27/10/2013 11:11, Wei Liu wrote: >> time_after_eq() only works if the delta is < MAX_ULONG/2. >> >> For a 32bit Dom0, if netfront sends packets at a very low rate, the time >> between subsequent calls to tx_credit_exceeded() may exceed MAX_ULONG/2 >> and the test for timer_after_eq() will be incorrect. Credit will not be >> replenished and the guest may become unable to send packets (e.g., if >> prior to the long gap, all credit was exhausted). >> >> Use jiffies_64 variant to mitigate this problem for 32bit Dom0. > Thanks. > >> Suggested-by: Jan Beulich <jbeulich@suse.com> >> Suggested-by: David Vrabel <david.vrabel@citrix.com> > Jan''s suggestion; I just agreed with him. > >> Signed-off-by: Wei Liu <wei.liu2@citrix.com> >> Cc: Ian Campbell <ian.campbell@citrix.com> >> Cc: Jason Luan <jianhai.luan@oracle.com> >> --- >> drivers/net/xen-netback/common.h | 1 + >> drivers/net/xen-netback/interface.c | 4 ++-- >> drivers/net/xen-netback/netback.c | 13 ++++++------- >> 3 files changed, 9 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h >> index 5715318..400fea1 100644 >> --- a/drivers/net/xen-netback/common.h >> +++ b/drivers/net/xen-netback/common.h >> @@ -163,6 +163,7 @@ struct xenvif { >> unsigned long credit_usec; >> unsigned long remaining_credit; >> struct timer_list credit_timeout; >> + u64 credit_window_start; >> >> /* Statistics */ >> unsigned long rx_gso_checksum_fixup; >> diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c >> index 01bb854..8c45b63 100644 >> --- a/drivers/net/xen-netback/interface.c >> +++ b/drivers/net/xen-netback/interface.c >> @@ -312,8 +312,8 @@ struct xenvif *xenvif_alloc(struct device *parent, domid_t domid, >> vif->credit_bytes = vif->remaining_credit = ~0UL; >> vif->credit_usec = 0UL; >> init_timer(&vif->credit_timeout); >> - /* Initialize ''expires'' now: it''s used to track the credit window. */ >> - vif->credit_timeout.expires = jiffies; >> + /* credit window is tracked in credit_window_start */ > You could drop this comment as the field name makes this obvious. > >> + vif->credit_window_start = get_jiffies_64(); >> >> dev->netdev_ops = &xenvif_netdev_ops; >> dev->hw_features = NETIF_F_SG | NETIF_F_IP_CSUM | NETIF_F_TSO; >> diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c >> index f3e591c..1bc0688 100644 >> --- a/drivers/net/xen-netback/netback.c >> +++ b/drivers/net/xen-netback/netback.c >> @@ -1185,18 +1185,17 @@ out: >> >> static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) >> { >> - unsigned long now = jiffies; >> - unsigned long next_credit >> - vif->credit_timeout.expires + >> - msecs_to_jiffies(vif->credit_usec / 1000); >> + u64 now = get_jiffies_64(); >> + u64 next_credit = vif->credit_window_start + >> + (u64)msecs_to_jiffies(vif->credit_usec / 1000); >> >> /* Timer could already be pending in rare cases. */ >> if (timer_pending(&vif->credit_timeout)) >> return true; >> >> /* Passed the point where we can replenish credit? */ >> - if (time_after_eq(now, next_credit)) { >> - vif->credit_timeout.expires = now; >> + if (time_after_eq64(now, next_credit)) { >> + vif->credit_timeout.expires = (unsigned long)now; > Need to set vif->credit_window_start = now here instead of .expires.I agree Annie''s suggest. add the below line; vif->credit_window_start = now vif->credit_timeout.expires = (unsigned long)now;>> tx_add_credit(vif); >> } >> >> @@ -1207,7 +1206,7 @@ static bool tx_credit_exceeded(struct xenvif *vif, unsigned size) >> vif->credit_timeout.function >> tx_credit_callback; >> mod_timer(&vif->credit_timeout, >> - next_credit); >> + (unsigned long)next_credit); > Need to set vif->credit_window_start = next_credit here as well.I think that we shouldn''t add the above line.> > DavidJason
Wei Liu
2013-Oct-28 11:30 UTC
Re: [PATCH net] xen-netback: use jiffies_64 value to calculate credit timeout
On Mon, Oct 28, 2013 at 10:58:32AM +0800, annie li wrote: [...]> >> if (timer_pending(&vif->credit_timeout)) > >> return true; > >> /* Passed the point where we can replenish credit? */ > >>- if (time_after_eq(now, next_credit)) { > >>- vif->credit_timeout.expires = now; > >>+ if (time_after_eq64(now, next_credit)) { > >>+ vif->credit_timeout.expires = (unsigned long)now; > > > >updates credit_window_start as following, > >vif->credit_window_start = (unsigned long)now; > > both credit_window_start and credit_timeout.expires need to be > updated here, > > vif->credit_window_start = (unsigned long)now; > vif->credit_timeout.expires = (unsigned long)now; >IMHO we don''t need to update .expires anymore -- we now track the window with another variable. Wei.