| Message ID | 20130124140441.14119.1878.stgit@dragon |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Jesper Dangaard Brouer <brouer@redhat.com> Date: Thu, 24 Jan 2013 15:04:53 +0100 > diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h > index b9df9ed..eded1aa 100644 > --- a/include/linux/percpu_counter.h > +++ b/include/linux/percpu_counter.h > @@ -83,7 +83,7 @@ static inline int percpu_counter_initialized(struct percpu_counter *fbc) > return (fbc->counters != NULL); > } > > -#else > +#else /* No CONFIG_SMP */ > > struct percpu_counter { > s64 count; This is unrelated to your changes, please remove this from the patch. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2013-01-28 at 23:24 -0500, David Miller wrote: > From: Jesper Dangaard Brouer <brouer@redhat.com> > Date: Thu, 24 Jan 2013 15:04:53 +0100 > > > diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h > > index b9df9ed..eded1aa 100644 > > --- a/include/linux/percpu_counter.h > > +++ b/include/linux/percpu_counter.h > > @@ -83,7 +83,7 @@ static inline int percpu_counter_initialized(struct percpu_counter *fbc) > > return (fbc->counters != NULL); > > } > > > > -#else > > +#else /* No CONFIG_SMP */ > > > > struct percpu_counter { > > s64 count; > > This is unrelated to your changes, please remove this from the patch. Understood, thanks for noticing. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/percpu_counter.h b/include/linux/percpu_counter.h index b9df9ed..eded1aa 100644 --- a/include/linux/percpu_counter.h +++ b/include/linux/percpu_counter.h @@ -83,7 +83,7 @@ static inline int percpu_counter_initialized(struct percpu_counter *fbc) return (fbc->counters != NULL); } -#else +#else /* No CONFIG_SMP */ struct percpu_counter { s64 count; diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index 9f69514..85db72e 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -1,14 +1,17 @@ #ifndef __NET_FRAG_H__ #define __NET_FRAG_H__ +#include <linux/percpu_counter.h> + struct netns_frags { int nqueues; struct list_head lru_list; - /* Its important for performance to keep lru_list and mem on - * separate cachelines + /* The percpu_counter "mem" need to be cacheline aligned. + * mem.count must not share cacheline with other writers */ - atomic_t mem ____cacheline_aligned_in_smp; + struct percpu_counter mem ____cacheline_aligned_in_smp; + /* sysctls */ int timeout; int high_thresh; @@ -82,29 +85,36 @@ static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f /* Memory Tracking Functions. */ +/* The default percpu_counter batch size is not big enough to scale to + * fragmentation mem acct sizes. + * The mem size of a 64K fragment is approx: + * (44 fragments * 2944 truesize) + frag_queue struct(200) = 129736 bytes + */ +static unsigned int frag_percpu_counter_batch = 130000; + static inline int frag_mem_limit(struct netns_frags *nf) { - return atomic_read(&nf->mem); + return percpu_counter_read(&nf->mem); } static inline void sub_frag_mem_limit(struct inet_frag_queue *q, int i) { - atomic_sub(i, &q->net->mem); + __percpu_counter_add(&q->net->mem, -i, frag_percpu_counter_batch); } static inline void add_frag_mem_limit(struct inet_frag_queue *q, int i) { - atomic_add(i, &q->net->mem); + __percpu_counter_add(&q->net->mem, i, frag_percpu_counter_batch); } static inline void init_frag_mem_limit(struct netns_frags *nf) { - atomic_set(&nf->mem, 0); + percpu_counter_init(&nf->mem, 0); } static inline int sum_frag_mem_limit(struct netns_frags *nf) { - return atomic_read(&nf->mem); + return percpu_counter_sum_positive(&nf->mem); } #endif diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index e348c84..b825205 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -91,6 +91,8 @@ void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f) local_bh_disable(); inet_frag_evictor(nf, f, true); local_bh_enable(); + + percpu_counter_destroy(&nf->mem); } EXPORT_SYMBOL(inet_frags_exit_net);
Replace the per network namespace shared atomic "mem" accounting variable, in the fragmentation code, with a lib/percpu_counter. Getting percpu_counter to scale to the fragmentation code usage requires some tweaks. At first view, percpu_counter looks superfast, but it does not scale on multi-CPU/NUMA machines, because the default batch size is too small, for frag code usage. Thus, I have adjusted the batch size by using __percpu_counter_add() directly, instead of percpu_counter_sub() and percpu_counter_add(). The batch size is increased to 130.000, based on the largest 64K fragment memory usage. This does introduce some imprecise memory accounting, but its does not need to be strict for this use-case. It is also essential, that the percpu_counter, does not share cacheline with other writers, to make this scale. Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> --- include/linux/percpu_counter.h | 2 +- include/net/inet_frag.h | 26 ++++++++++++++++++-------- net/ipv4/inet_fragment.c | 2 ++ 3 files changed, 21 insertions(+), 9 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html