[dpdk-dev] [PATCH v3 1/3] lib/lpm: not inline unnecessary functions

[Honnappa Nagarahalli]

> Hi all,
> 
> On 28/06/2019 05:34, Stephen Hemminger wrote:
> > On Fri, 28 Jun 2019 02:44:54 +0000
> > "Ruifeng Wang (Arm Technology China)"<Ruifeng.Wang at arm.com>  wrote:
> >
> >>>
> >>>> Tests showed that the function inlining caused performance drop on
> >>>> some x86 platforms with the memory ordering patches applied.
> >>>> By force no-inline functions, the performance was better than
> >>>> before on x86 and no impact to arm64 platforms.
> >>>>
> >>>> Suggested-by: Medvedkin Vladimir<vladimir.medvedkin at intel.com>
> >>>> Signed-off-by: Ruifeng Wang<ruifeng.wang at arm.com>
> >>>> Reviewed-by: Gavin Hu<gavin.hu at arm.com>
> >>>   {
> >>>
> >>> Do you actually need to force noinline or is just taking of inline enough?
> >>> In general, letting compiler decide is often best practice.
> >> The force noinline is an optimization for x86 platforms to keep
> >> rte_lpm_add() API performance with memory ordering applied.
> > I don't think you answered my question. What does a recent version of
> > GCC do if you drop the inline.
> >
> > Actually all the functions in rte_lpm should drop inline.
> I'm agree with Stephen. If it is not a fastpath and size of function is not
> minimal it is good to remove inline qualifier for other control plane functions
> such as rule_add/delete/find/etc and let the compiler decide to inline it
> (unless it affects performance).
IMO, the rule needs to be simple. If it is control plane function, we should leave it to the compiler to decide. I do not think we need to worry too much about performance for control plane functions.

> > diff --git a/lib/librte_lpm/rte_lpm.c b/lib/librte_lpm/rte_lpm.c index
> > 6b7b28a2e431..ffe07e980864 100644
> > --- a/lib/librte_lpm/rte_lpm.c
> > +++ b/lib/librte_lpm/rte_lpm.c
> > @@ -399,7 +399,7 @@ MAP_STATIC_SYMBOL(void rte_lpm_free(struct
> rte_lpm *lpm),
> >    * are stored in the rule table from 0 - 31.
> >    * NOTE: Valid range for depth parameter is 1 .. 32 inclusive.
> >    */
> > -static inline int32_t
> > +static int32_t
> >   rule_add_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, uint8_t
> depth,
> >   	uint8_t next_hop)
> >   {
> > @@ -471,7 +471,7 @@ rule_add_v20(struct rte_lpm_v20 *lpm, uint32_t
> ip_masked, uint8_t depth,
> >   	return rule_index;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   rule_add_v1604(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth,
> >   	uint32_t next_hop)
> >   {
> > @@ -547,7 +547,7 @@ rule_add_v1604(struct rte_lpm *lpm, uint32_t
> ip_masked, uint8_t depth,
> >    * Delete a rule from the rule table.
> >    * NOTE: Valid range for depth parameter is 1 .. 32 inclusive.
> >    */
> > -static inline void
> > +static void
> >   rule_delete_v20(struct rte_lpm_v20 *lpm, int32_t rule_index, uint8_t
> depth)
> >   {
> >   	int i;
> > @@ -570,7 +570,7 @@ rule_delete_v20(struct rte_lpm_v20 *lpm, int32_t
> rule_index, uint8_t depth)
> >   	lpm->rule_info[depth - 1].used_rules--;
> >   }
> >
> > -static inline void
> > +static void
> >   rule_delete_v1604(struct rte_lpm *lpm, int32_t rule_index, uint8_t depth)
> >   {
> >   	int i;
> > @@ -597,7 +597,7 @@ rule_delete_v1604(struct rte_lpm *lpm, int32_t
> rule_index, uint8_t depth)
> >    * Finds a rule in rule table.
> >    * NOTE: Valid range for depth parameter is 1 .. 32 inclusive.
> >    */
> > -static inline int32_t
> > +static int32_t
> >   rule_find_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, uint8_t
> depth)
> >   {
> >   	uint32_t rule_gindex, last_rule, rule_index; @@ -618,7 +618,7 @@
> > rule_find_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked, uint8_t depth)
> >   	return -EINVAL;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   rule_find_v1604(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth)
> >   {
> >   	uint32_t rule_gindex, last_rule, rule_index; @@ -642,7 +642,7 @@
> > rule_find_v1604(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t depth)
> >   /*
> >    * Find, clean and allocate a tbl8.
> >    */
> > -static inline int32_t
> > +static int32_t
> >   tbl8_alloc_v20(struct rte_lpm_tbl_entry_v20 *tbl8)
> >   {
> >   	uint32_t group_idx; /* tbl8 group index. */ @@ -669,7 +669,7 @@
> > tbl8_alloc_v20(struct rte_lpm_tbl_entry_v20 *tbl8)
> >   	return -ENOSPC;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   tbl8_alloc_v1604(struct rte_lpm_tbl_entry *tbl8, uint32_t number_tbl8s)
> >   {
> >   	uint32_t group_idx; /* tbl8 group index. */ @@ -709,7 +709,7 @@
> > tbl8_free_v1604(struct rte_lpm_tbl_entry *tbl8, uint32_t tbl8_group_start)
> >   	tbl8[tbl8_group_start].valid_group = INVALID;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   add_depth_small_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t depth,
> >   		uint8_t next_hop)
> >   {
> > @@ -777,7 +777,7 @@ add_depth_small_v20(struct rte_lpm_v20 *lpm,
> uint32_t ip, uint8_t depth,
> >   	return 0;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   add_depth_small_v1604(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
> >   		uint32_t next_hop)
> >   {
> > @@ -846,7 +846,7 @@ add_depth_small_v1604(struct rte_lpm *lpm,
> uint32_t ip, uint8_t depth,
> >   	return 0;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   add_depth_big_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked,
> uint8_t depth,
> >   		uint8_t next_hop)
> >   {
> > @@ -971,7 +971,7 @@ add_depth_big_v20(struct rte_lpm_v20 *lpm,
> uint32_t ip_masked, uint8_t depth,
> >   	return 0;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   add_depth_big_v1604(struct rte_lpm *lpm, uint32_t ip_masked, uint8_t
> depth,
> >   		uint32_t next_hop)
> >   {
> > @@ -1244,7 +1244,7 @@
> BIND_DEFAULT_SYMBOL(rte_lpm_is_rule_present, _v1604, 16.04);
> >   MAP_STATIC_SYMBOL(int rte_lpm_is_rule_present(struct rte_lpm *lpm,
> uint32_t ip,
> >   		uint8_t depth, uint32_t *next_hop),
> > rte_lpm_is_rule_present_v1604);
> >
> > -static inline int32_t
> > +static int32_t
> >   find_previous_rule_v20(struct rte_lpm_v20 *lpm, uint32_t ip, uint8_t
> depth,
> >   		uint8_t *sub_rule_depth)
> >   {
> > @@ -1266,7 +1266,7 @@ find_previous_rule_v20(struct rte_lpm_v20
> *lpm, uint32_t ip, uint8_t depth,
> >   	return -1;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   find_previous_rule_v1604(struct rte_lpm *lpm, uint32_t ip, uint8_t depth,
> >   		uint8_t *sub_rule_depth)
> >   {
> > @@ -1288,7 +1288,7 @@ find_previous_rule_v1604(struct rte_lpm *lpm,
> uint32_t ip, uint8_t depth,
> >   	return -1;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   delete_depth_small_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked,
> >   	uint8_t depth, int32_t sub_rule_index, uint8_t sub_rule_depth)
> >   {
> > @@ -1381,7 +1381,7 @@ delete_depth_small_v20(struct rte_lpm_v20
> *lpm, uint32_t ip_masked,
> >   	return 0;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   delete_depth_small_v1604(struct rte_lpm *lpm, uint32_t ip_masked,
> >   	uint8_t depth, int32_t sub_rule_index, uint8_t sub_rule_depth)
> >   {
> > @@ -1483,7 +1483,7 @@ delete_depth_small_v1604(struct rte_lpm *lpm,
> uint32_t ip_masked,
> >    * Return of value > -1 means tbl8 is in use but has all the same values and
> >    * thus can be recycled
> >    */
> > -static inline int32_t
> > +static int32_t
> >   tbl8_recycle_check_v20(struct rte_lpm_tbl_entry_v20 *tbl8,
> >   		uint32_t tbl8_group_start)
> >   {
> > @@ -1530,7 +1530,7 @@ tbl8_recycle_check_v20(struct
> rte_lpm_tbl_entry_v20 *tbl8,
> >   	return -EINVAL;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   tbl8_recycle_check_v1604(struct rte_lpm_tbl_entry *tbl8,
> >   		uint32_t tbl8_group_start)
> >   {
> > @@ -1577,7 +1577,7 @@ tbl8_recycle_check_v1604(struct
> rte_lpm_tbl_entry *tbl8,
> >   	return -EINVAL;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   delete_depth_big_v20(struct rte_lpm_v20 *lpm, uint32_t ip_masked,
> >   	uint8_t depth, int32_t sub_rule_index, uint8_t sub_rule_depth)
> >   {
> > @@ -1655,7 +1655,7 @@ delete_depth_big_v20(struct rte_lpm_v20 *lpm,
> uint32_t ip_masked,
> >   	return 0;
> >   }
> >
> > -static inline int32_t
> > +static int32_t
> >   delete_depth_big_v1604(struct rte_lpm *lpm, uint32_t ip_masked,
> >   	uint8_t depth, int32_t sub_rule_index, uint8_t sub_rule_depth)
> >   {
> 
> --
> Regards,
> Vladimir