Messages in this thread | | | Date | Tue, 9 Apr 2024 17:21:49 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH net-next v2 4/4] net: dqs: make struct dql more cache efficient |
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On Mon, 8 Apr 2024 10:25:56 -0700 Breno Leitao wrote: > With the previous change, struct dqs->stall_thrs will be in the hot path > (at queue side), even if DQS is disabled. > > The other fields accessed in this function (last_obj_cnt and num_queued) > are in the first cache line, let's move this field (stall_thrs) to the > very first cache line, since there is a hole there. > > This does not change the structure size, since it moves an short (2 > bytes) to 4-bytes whole in the first cache line.
Doesn't this move the cache line bouncing problem to the other side? Eric said "copy" I read that as "have two fields with the same value". I think it's single digit number of alu instructions we'd be saving here, not super convinced patch 3 is the right trade off...
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