* [PATCH -next] hfsc: reduce hfsc_sched to 14 cachelines
@ 2016-07-04 14:22 Florian Westphal
2016-07-04 17:57 ` Michal Soltys
2016-07-09 3:09 ` David Miller
0 siblings, 2 replies; 3+ messages in thread
From: Florian Westphal @ 2016-07-04 14:22 UTC (permalink / raw)
To: netdev; +Cc: Florian Westphal, Michal Soltys
hfsc_sched is huge (size: 920, cachelines: 15), but we can get it to 14
cachelines by placing level after filter_cnt (covering 4 byte hole) and
reducing period/nactive/flags to u32 (period is just a counter,
incremented when class becomes active -- 2**32 is plenty for this
purpose, also, long is only 32bit wide on 32bit platforms anyway).
cl_vtperiod is exported to userspace via tc_hfsc_stats, but its period
member is already u32, so no precision is lost there either.
Cc: Michal Soltys <soltys@ziu.info>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
net/sched/sch_hfsc.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 0fd8da7..6a6fb30 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -115,9 +115,9 @@ struct hfsc_class {
struct gnet_stats_basic_packed bstats;
struct gnet_stats_queue qstats;
struct gnet_stats_rate_est64 rate_est;
- unsigned int level; /* class level in hierarchy */
struct tcf_proto __rcu *filter_list; /* filter list */
unsigned int filter_cnt; /* filter count */
+ unsigned int level; /* class level in hierarchy */
struct hfsc_sched *sched; /* scheduler data */
struct hfsc_class *cl_parent; /* parent class */
@@ -165,10 +165,10 @@ struct hfsc_class {
struct runtime_sc cl_virtual; /* virtual curve */
struct runtime_sc cl_ulimit; /* upperlimit curve */
- unsigned long cl_flags; /* which curves are valid */
- unsigned long cl_vtperiod; /* vt period sequence number */
- unsigned long cl_parentperiod;/* parent's vt period sequence number*/
- unsigned long cl_nactive; /* number of active children */
+ u8 cl_flags; /* which curves are valid */
+ u32 cl_vtperiod; /* vt period sequence number */
+ u32 cl_parentperiod;/* parent's vt period sequence number*/
+ u32 cl_nactive; /* number of active children */
};
struct hfsc_sched {
--
2.7.3
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH -next] hfsc: reduce hfsc_sched to 14 cachelines
2016-07-04 14:22 [PATCH -next] hfsc: reduce hfsc_sched to 14 cachelines Florian Westphal
@ 2016-07-04 17:57 ` Michal Soltys
2016-07-09 3:09 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: Michal Soltys @ 2016-07-04 17:57 UTC (permalink / raw)
To: Florian Westphal, netdev
On 2016-07-04 16:22, Florian Westphal wrote:
> hfsc_sched is huge (size: 920, cachelines: 15), but we can get it to 14
> cachelines by placing level after filter_cnt (covering 4 byte hole) and
> reducing period/nactive/flags to u32 (period is just a counter,
> incremented when class becomes active -- 2**32 is plenty for this
> purpose, also, long is only 32bit wide on 32bit platforms anyway).
>
> cl_vtperiod is exported to userspace via tc_hfsc_stats, but its period
> member is already u32, so no precision is lost there either.
>
It should be fine, even if it overflowed (which theoretically isn't that
hard: 1500 mtu, 1gbit interface, 900mbit transfer (meaning some process
throttling itself to 900mbit, not hfsc upperlimiting it) => ~16 hours to
overflow or ITOW 75000 period changes/s) - what really matters (in
init_vf()) is if the period is different.
For the record, I have 2 patches that will trim some stuff further.
Unfortunately I have another 2 that will near surely put it back at
[hopefully only] 16 (if they get accepted that is).
But there're some other candidates that might help (some not that tiny
functions defined as inline that are called in more than 1 place). E.g.
update_cfmin() is called from 3 places.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH -next] hfsc: reduce hfsc_sched to 14 cachelines
2016-07-04 14:22 [PATCH -next] hfsc: reduce hfsc_sched to 14 cachelines Florian Westphal
2016-07-04 17:57 ` Michal Soltys
@ 2016-07-09 3:09 ` David Miller
1 sibling, 0 replies; 3+ messages in thread
From: David Miller @ 2016-07-09 3:09 UTC (permalink / raw)
To: fw; +Cc: netdev, soltys
From: Florian Westphal <fw@strlen.de>
Date: Mon, 4 Jul 2016 16:22:20 +0200
> hfsc_sched is huge (size: 920, cachelines: 15), but we can get it to 14
> cachelines by placing level after filter_cnt (covering 4 byte hole) and
> reducing period/nactive/flags to u32 (period is just a counter,
> incremented when class becomes active -- 2**32 is plenty for this
> purpose, also, long is only 32bit wide on 32bit platforms anyway).
>
> cl_vtperiod is exported to userspace via tc_hfsc_stats, but its period
> member is already u32, so no precision is lost there either.
>
> Cc: Michal Soltys <soltys@ziu.info>
> Signed-off-by: Florian Westphal <fw@strlen.de>
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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