search for: write_seqcount_end

...or) + if (action & TK_MIRROR) memcpy(&shadow_timekeeper, &timekeeper, sizeof(timekeeper)); } @@ -508,7 +511,7 @@ int do_settimeofday(const struct timespec *tv) tk_set_xtime(tk, tv); - timekeeping_update(tk, true, true); + timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR); write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); @@ -552,7 +555,7 @@ int timekeeping_inject_offset(struct timespec *ts) tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *ts)); error: /* even if we error out, we forwarded the time, so call update */...

..._set_task, 0); + +static void timekeeping_clock_was_set_delayed(void) +{ + tasklet_schedule(&clock_was_set_tasklet); +} + static RAW_NOTIFIER_HEAD(pvclock_gtod_chain); static void update_pvclock_gtod(struct timekeeper *tk) @@ -513,8 +532,7 @@ int do_settimeofday(const struct timespec *tv) write_seqcount_end(&timekeeper_seq); raw_spin_unlock_irqrestore(&timekeeper_lock, flags); - /* signal hrtimers about time change */ - clock_was_set(); + timekeeping_clock_was_set(); return 0; } @@ -557,8 +575,7 @@ error: /* even if we error out, we forwarded the time, so call update */ write_seqcou...

...ctly. 1199 */ 1200 if (dev->flags & IFF_UP && 1201 likely(!(dev->priv_flags & IFF_FAILOVER_SLAVE))) 1202 return -EBUSY; 1203 1204 write_seqcount_begin(&devnet_rename_seq); 1205 1206 if (strncmp(newname, dev->name, IFNAMSIZ) == 0) { 1207 write_seqcount_end(&devnet_rename_seq); 1208 return 0; 1209 } 1210 1211 memcpy(oldname, dev->name, IFNAMSIZ); 1212 1213 err = dev_get_valid_name(net, dev, newname); 1214 if (err < 0) { 1215 write_seqcount_end(&devnet_rename_seq); 1216 return err; 1217 } 1218 1219 i...

...gt;flags & IFF_UP) { 1202 if (likely(!(dev->priv_flags & IFF_FAILOVER_SLAVE))) 1203 return -EBUSY; 1204 reopen_needed = true; 1205 } 1206 1207 write_seqcount_begin(&devnet_rename_seq); 1208 1209 if (strncmp(newname, dev->name, IFNAMSIZ) == 0) { 1210 write_seqcount_end(&devnet_rename_seq); 1211 return 0; 1212 } 1213 1214 memcpy(oldname, dev->name, IFNAMSIZ); 1215 1216 err = dev_get_valid_name(net, dev, newname); 1217 if (err < 0) { 1218 write_seqcount_end(&devnet_rename_seq); 1219 return err; 1220 } 1221 1222 i...

...!strchr(oldname, '%')) > netdev_info(dev, "renamed from %s\n", oldname); > >@@ -1210,7 +1230,9 @@ int dev_change_name(struct net_device *dev, const char *newname) > memcpy(dev->name, oldname, IFNAMSIZ); > dev->name_assign_type = old_assign_type; > write_seqcount_end(&devnet_rename_seq); >- return ret; >+ if (err >= 0) >+ err = ret; >+ goto reopen; > } > > write_seqcount_end(&devnet_rename_seq); >@@ -1246,6 +1268,15 @@ int dev_change_name(struct net_device *dev, const char *newname) > } > } > >+reopen:...

...> uaddr->uaddr - 1 + uaddr->size); > } > > +static void inline vhost_vq_access_map_begin(struct vhost_virtqueue *vq) > +{ > + write_seqcount_begin(&vq->seq); > +} > + > +static void inline vhost_vq_access_map_end(struct vhost_virtqueue *vq) > +{ > + write_seqcount_end(&vq->seq); > +} The write side of a seqlock only provides write barriers. Access to map = vq->maps[VHOST_ADDR_USED]; Still needs a read side barrier, and then I think this will be no better than a normal spinlock. It also doesn't seem like this algorithm even needs a seqlock,...

...> uaddr->uaddr - 1 + uaddr->size); > } > > +static void inline vhost_vq_access_map_begin(struct vhost_virtqueue *vq) > +{ > + write_seqcount_begin(&vq->seq); > +} > + > +static void inline vhost_vq_access_map_end(struct vhost_virtqueue *vq) > +{ > + write_seqcount_end(&vq->seq); > +} The write side of a seqlock only provides write barriers. Access to map = vq->maps[VHOST_ADDR_USED]; Still needs a read side barrier, and then I think this will be no better than a normal spinlock. It also doesn't seem like this algorithm even needs a seqlock,...

...ford that for vhost fast path, the atomics eliminate almost all the performance improvement brought by this patch on a machine without SMAP. > >> write_seqcount_begin() >> >> map = vq->map[X] >> >> write or read through map->addr directly >> >> write_seqcount_end() >> >> >> There's no rmb() in write_seqcount_begin(), so map could be read before >> write_seqcount_begin(), but it looks to me now that this doesn't harm at >> all, maybe we can try this way. > That is because it is a write side lock, not a read lock. IIRC...

...gister cycle. You are supposed to use something simple like a spinlock or mutex inside the invalidate_range_start to serialized tear down of the SPTEs with their accessors. > write_seqcount_begin() > > map = vq->map[X] > > write or read through map->addr directly > > write_seqcount_end() > > > There's no rmb() in write_seqcount_begin(), so map could be read before > write_seqcount_begin(), but it looks to me now that this doesn't harm at > all, maybe we can try this way. That is because it is a write side lock, not a read lock. IIRC seqlocks have weaker...

...gister cycle. You are supposed to use something simple like a spinlock or mutex inside the invalidate_range_start to serialized tear down of the SPTEs with their accessors. > write_seqcount_begin() > > map = vq->map[X] > > write or read through map->addr directly > > write_seqcount_end() > > > There's no rmb() in write_seqcount_begin(), so map could be read before > write_seqcount_begin(), but it looks to me now that this doesn't harm at > all, maybe we can try this way. That is because it is a write side lock, not a read lock. IIRC seqlocks have weaker...

...addr, return !(end < uaddr->uaddr || start > uaddr->uaddr - 1 + uaddr->size); } +static void inline vhost_vq_access_map_begin(struct vhost_virtqueue *vq) +{ + write_seqcount_begin(&vq->seq); +} + +static void inline vhost_vq_access_map_end(struct vhost_virtqueue *vq) +{ + write_seqcount_end(&vq->seq); +} + +static void inline vhost_vq_sync_access(struct vhost_virtqueue *vq) +{ + unsigned int seq; + + /* Make sure any changes to map was done before checking seq + * counter. Paired with smp_wmb() in write_seqcount_begin(). + */ + smp_mb(); + seq = raw_read_seqcount(&vq->...

...id inline vhost_vq_access_map_begin(struct >>> vhost_virtqueue *vq) >>> +{ >>> +??? write_seqcount_begin(&vq->seq); >>> +} >>> + >>> +static void inline vhost_vq_access_map_end(struct vhost_virtqueue *vq) >>> +{ >>> +??? write_seqcount_end(&vq->seq); >>> +} >> The write side of a seqlock only provides write barriers. Access to >> >> ????map = vq->maps[VHOST_ADDR_USED]; >> >> Still needs a read side barrier, and then I think this will be no >> better than a normal spinlock. >&g...

...); >> } >> >> +static void inline vhost_vq_access_map_begin(struct vhost_virtqueue *vq) >> +{ >> + write_seqcount_begin(&vq->seq); >> +} >> + >> +static void inline vhost_vq_access_map_end(struct vhost_virtqueue *vq) >> +{ >> + write_seqcount_end(&vq->seq); >> +} > The write side of a seqlock only provides write barriers. Access to > > map = vq->maps[VHOST_ADDR_USED]; > > Still needs a read side barrier, and then I think this will be no > better than a normal spinlock. > > It also doesn't seem li...

Hi all: This series try to fix several issues introduced by meta data accelreation series. Please review. Changes from V3: - remove the unnecessary patch Changes from V2: - use seqlck helper to synchronize MMU notifier with vhost worker Changes from V1: - try not use RCU to syncrhonize MMU notifier with vhost worker - set dirty pages after no readers - return -EAGAIN only when we find the

Hi all: This series try to fix several issues introduced by meta data accelreation series. Please review. Changes from V3: - remove the unnecessary patch Changes from V2: - use seqlck helper to synchronize MMU notifier with vhost worker Changes from V1: - try not use RCU to syncrhonize MMU notifier with vhost worker - set dirty pages after no readers - return -EAGAIN only when we find the

...t sysfs_seq; + /* Page frag for packet buffer allocation. */ struct page_frag alloc_frag; @@ -416,7 +423,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, } } + write_seqcount_begin(&rq->sysfs_seq); ewma_add(&rq->mrg_avg_pkt_len, head_skb->len); + write_seqcount_end(&rq->sysfs_seq); return head_skb; err_skb: @@ -604,18 +613,29 @@ static int add_recvbuf_big(struct receive_queue *rq, gfp_t gfp) return err; } -static int add_recvbuf_mergeable(struct receive_queue *rq, gfp_t gfp) +static unsigned int get_mergeable_buf_len(struct ewma *avg_pkt_len)...

On Wed, Jul 31, 2019 at 04:46:53AM -0400, Jason Wang wrote: > We used to use RCU to synchronize MMU notifier with worker. This leads > calling synchronize_rcu() in invalidate_range_start(). But on a busy > system, there would be many factors that may slow down the > synchronize_rcu() which makes it unsuitable to be called in MMU > notifier. > > A solution is SRCU but its

On Wed, Jul 31, 2019 at 04:46:53AM -0400, Jason Wang wrote: > We used to use RCU to synchronize MMU notifier with worker. This leads > calling synchronize_rcu() in invalidate_range_start(). But on a busy > system, there would be many factors that may slow down the > synchronize_rcu() which makes it unsuitable to be called in MMU > notifier. > > A solution is SRCU but its

...er allocation. */ > struct page_frag alloc_frag; > > @@ -416,7 +423,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > } > } > > + write_seqcount_begin(&rq->sysfs_seq); > ewma_add(&rq->mrg_avg_pkt_len, head_skb->len); > + write_seqcount_end(&rq->sysfs_seq); > return head_skb; > > err_skb: Hmm this adds overhead just to prevent sysfs from getting wrong value. Can't sysfs simply disable softirq while it's reading the value? > @@ -604,18 +613,29 @@ static int add_recvbuf_big(struct receive_queue *rq, gfp...

...er allocation. */ > struct page_frag alloc_frag; > > @@ -416,7 +423,9 @@ static struct sk_buff *receive_mergeable(struct net_device *dev, > } > } > > + write_seqcount_begin(&rq->sysfs_seq); > ewma_add(&rq->mrg_avg_pkt_len, head_skb->len); > + write_seqcount_end(&rq->sysfs_seq); > return head_skb; > > err_skb: Hmm this adds overhead just to prevent sysfs from getting wrong value. Can't sysfs simply disable softirq while it's reading the value? > @@ -604,18 +613,29 @@ static int add_recvbuf_big(struct receive_queue *rq, gfp...