Messages in this thread | | | Date | Mon, 26 Nov 2001 11:29:19 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] Scalable page cache |
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"David S. Miller" wrote: > > From: Ingo Molnar <mingo@elte.hu> > Date: Mon, 26 Nov 2001 21:29:39 +0100 (CET) > > so i'm not against removing (or improving) the hash [our patch in fact > just left the hash alone], but the patch presented is not a win IMO. > > Maybe you should give it a test to find out for sure :)
umm.. I've never seen any numbers from you, David.
Correct me if I'm wrong, but the pagecache_hash cost is significant in the following situations:
1: TUX, because its pagecache lookups are not associated with a page copy. This copy makes the benefits of the patch unmeasurable with other workloads.
1a: Other sendfile-intensive applications. (Theoretical benefit. No benchmark results have been seen).
2: NUMA hardware, where the cost of cacheline transfer is much higher.
ergo, there is no point in futzing with the pagecache_lock *at all* until either TUX is merged, or we decide to support large-scale NUMA hardware well, which will require changes in other places.
Prove me wrong. Please.
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