service: improve service run performance
Checks
Commit Message
For a valid service, the core mask of the service
is checked against the current core and the corresponding
entry in the active_on_lcore array is set or reset.
Upto 8 cores share the same cache line for their
service active_on_lcore array entries since each entry is a uint8_t.
Some number of these entries also share the cache line with
the internal_flags member of struct rte_service_spec_impl,
hence this false sharing also makes the service_valid() check
expensive.
Eliminate false sharing by moving the active_on_lcore array to
a per-core data structure. The array is now indexed by service id.
Signed-off-by: Nikhil Rao <nikhil.rao@intel.com>
---
lib/librte_eal/common/rte_service.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
Comments
On Mon, Sep 16, 2019 at 12:01 PM Nikhil Rao <nikhil.rao@intel.com> wrote:
>
> For a valid service, the core mask of the service
> is checked against the current core and the corresponding
> entry in the active_on_lcore array is set or reset.
>
> Upto 8 cores share the same cache line for their
> service active_on_lcore array entries since each entry is a uint8_t.
> Some number of these entries also share the cache line with
> the internal_flags member of struct rte_service_spec_impl,
> hence this false sharing also makes the service_valid() check
> expensive.
>
> Eliminate false sharing by moving the active_on_lcore array to
> a per-core data structure. The array is now indexed by service id.
Harry, any comments on this patch?
Thanks.
> -----Original Message-----
> From: David Marchand [mailto:david.marchand@redhat.com]
> Sent: Monday, October 7, 2019 3:53 PM
> To: Van Haaren, Harry <harry.van.haaren@intel.com>
> Cc: dev <dev@dpdk.org>; Rao, Nikhil <nikhil.rao@intel.com>
> Subject: Re: [dpdk-dev] [PATCH] service: improve service run performance
>
> On Mon, Sep 16, 2019 at 12:01 PM Nikhil Rao <nikhil.rao@intel.com> wrote:
> >
> > For a valid service, the core mask of the service
> > is checked against the current core and the corresponding
> > entry in the active_on_lcore array is set or reset.
> >
> > Upto 8 cores share the same cache line for their
> > service active_on_lcore array entries since each entry is a uint8_t.
> > Some number of these entries also share the cache line with
> > the internal_flags member of struct rte_service_spec_impl,
> > hence this false sharing also makes the service_valid() check
> > expensive.
> >
> > Eliminate false sharing by moving the active_on_lcore array to
> > a per-core data structure. The array is now indexed by service id.
>
> Harry, any comments on this patch?
Looks good to me, thanks Nikhil & David for the ping;
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>
On Mon, Oct 7, 2019 at 5:37 PM Van Haaren, Harry
<harry.van.haaren@intel.com> wrote:
>
> > -----Original Message-----
> > From: David Marchand [mailto:david.marchand@redhat.com]
> > Sent: Monday, October 7, 2019 3:53 PM
> > To: Van Haaren, Harry <harry.van.haaren@intel.com>
> > Cc: dev <dev@dpdk.org>; Rao, Nikhil <nikhil.rao@intel.com>
> > Subject: Re: [dpdk-dev] [PATCH] service: improve service run performance
> >
> > On Mon, Sep 16, 2019 at 12:01 PM Nikhil Rao <nikhil.rao@intel.com> wrote:
> > >
> > > For a valid service, the core mask of the service
> > > is checked against the current core and the corresponding
> > > entry in the active_on_lcore array is set or reset.
> > >
> > > Upto 8 cores share the same cache line for their
> > > service active_on_lcore array entries since each entry is a uint8_t.
> > > Some number of these entries also share the cache line with
> > > the internal_flags member of struct rte_service_spec_impl,
> > > hence this false sharing also makes the service_valid() check
> > > expensive.
> > >
> > > Eliminate false sharing by moving the active_on_lcore array to
> > > a per-core data structure. The array is now indexed by service id.
Acked-by: Gage Eads <gage.eads@intel.com>
> >
> > Harry, any comments on this patch?
>
>
> Looks good to me, thanks Nikhil & David for the ping;
>
> Acked-by: Harry van Haaren <harry.van.haaren@intel.com>
Applied, thanks.
--
David Marchand
@@ -51,7 +51,6 @@ struct rte_service_spec_impl {
rte_atomic32_t num_mapped_cores;
uint64_t calls;
uint64_t cycles_spent;
- uint8_t active_on_lcore[RTE_MAX_LCORE];
} __rte_cache_aligned;
/* the internal values of a service core */
@@ -60,7 +59,7 @@ struct core_state {
uint64_t service_mask;
uint8_t runstate; /* running or stopped */
uint8_t is_service_core; /* set if core is currently a service core */
-
+ uint8_t service_active_on_lcore[RTE_SERVICE_NUM_MAX];
uint64_t loops;
uint64_t calls_per_service[RTE_SERVICE_NUM_MAX];
} __rte_cache_aligned;
@@ -347,7 +346,7 @@ int32_t rte_service_init(void)
static inline int32_t
-service_run(uint32_t i, int lcore, struct core_state *cs, uint64_t service_mask)
+service_run(uint32_t i, struct core_state *cs, uint64_t service_mask)
{
if (!service_valid(i))
return -EINVAL;
@@ -355,11 +354,11 @@ int32_t rte_service_init(void)
if (s->comp_runstate != RUNSTATE_RUNNING ||
s->app_runstate != RUNSTATE_RUNNING ||
!(service_mask & (UINT64_C(1) << i))) {
- s->active_on_lcore[lcore] = 0;
+ cs->service_active_on_lcore[i] = 0;
return -ENOEXEC;
}
- s->active_on_lcore[lcore] = 1;
+ cs->service_active_on_lcore[i] = 1;
/* check do we need cmpset, if MT safe or <= 1 core
* mapped, atomic ops are not required.
@@ -382,7 +381,6 @@ int32_t rte_service_init(void)
rte_service_may_be_active(uint32_t id)
{
uint32_t ids[RTE_MAX_LCORE] = {0};
- struct rte_service_spec_impl *s = &rte_services[id];
int32_t lcore_count = rte_service_lcore_list(ids, RTE_MAX_LCORE);
int i;
@@ -390,7 +388,7 @@ int32_t rte_service_init(void)
return -EINVAL;
for (i = 0; i < lcore_count; i++) {
- if (s->active_on_lcore[ids[i]])
+ if (lcore_states[i].service_active_on_lcore[id])
return 1;
}
@@ -421,7 +419,7 @@ int32_t rte_service_run_iter_on_app_lcore(uint32_t id,
return -EBUSY;
}
- int ret = service_run(id, rte_lcore_id(), cs, UINT64_MAX);
+ int ret = service_run(id, cs, UINT64_MAX);
if (serialize_mt_unsafe)
rte_atomic32_dec(&s->num_mapped_cores);
@@ -442,7 +440,7 @@ int32_t rte_service_run_iter_on_app_lcore(uint32_t id,
for (i = 0; i < RTE_SERVICE_NUM_MAX; i++) {
/* return value ignored as no change to code flow */
- service_run(i, lcore, cs, service_mask);
+ service_run(i, cs, service_mask);
}
cs->loops++;