On 03/02/17 19:28, Stephen Hemminger wrote: > On Fri, 3 Feb 2017 09:30:37 +0100 > Nikolay Aleksandrov <niko...@cumulusnetworks.com> wrote: > >> On 03/02/17 03:47, David Miller wrote: >>> From: Nikolay Aleksandrov <niko...@cumulusnetworks.com> >>> Date: Tue, 31 Jan 2017 16:31:58 +0100 >>> >>>> @@ -197,7 +197,8 @@ int br_handle_frame_finish(struct net *net, struct >>>> sock *sk, struct sk_buff *skb >>>> if (dst->is_local) >>>> return br_pass_frame_up(skb); >>>> >>>> - dst->used = jiffies; >>>> + if (br->used_enabled) >>>> + dst->used = jiffies; >>> >>> Have you tried: >>> >>> if (dst->used != jiffies) >>> dst->used = jiffies; >>> >>> If that isn't effective, you can tweak the test to decrease the >>> granularity of the value. Basically, if dst->used is within >>> 1 HZ of jiffies, don't do the write. >>> >>> I suspect this might help a lot, and not require a new bridging >>> option. >>> >> >> Yes, I actually have a patch titled "used granularity". :-) I've tested with >> different >> values and it does help but it either needs to be paired with another >> similar test for >> the "updated" field (since they share a write-heavy cache line) or they need >> to be >> in separate cache lines to avoid that dst's source port from causing the >> load HitM for >> all who check the value. >> >> I'll run some more tests and probably go this way for now. >> >> Thanks, >> Nik >> > > Since used doesn't need HZ granularity, it reports values in clock_t > resolution so > storing (and doing cmp and set would mean that it would only be 100 HZ >
Yes, exactly what I'm currently testing. Will post the new set soon. Since HZ can be different a generic way to obtain the granularity for both should be clock_t_to_jiffies(1) if I'm not missing something.
