Messages in this thread | | | Date | Tue, 16 Feb 2016 14:29:46 -0500 | From | Johannes Weiner <> | Subject | Re: Unhelpful caching decisions, possibly related to active/inactive sizing |
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On Fri, Feb 12, 2016 at 08:35:53PM +0100, Andres Freund wrote: > To make an actually usable patch out of this it seems we'd have to add a > 'partial' argument to grab_cache_page_write_begin(), so writes to parts > of a page still cause the pages to be marked active. Is it preferrable > to change all callers of grab_cache_page_write_begin and > add_to_page_cache_lru or make them into wrapper functions, and call the > real deal when it matters?
Personally, I'd prefer explicit arguments over another layer of wrappers, especially in the add_to_page_cache family. But it's possible others will disagree and only voice their opinion once you went through the hassle and sent a patch.
> I do think that that's a reasonable algorithmic change, but nonetheless > its obviously possible that such changes regress some workloads. What's > the policy around testing such things?
How about a FGP_WRITE that only sets the page's referenced bit, but doesn't activate or refault-activate the page?
That way, pages that are only ever written would never get activated, but a single read mixed in would activate the page straightaway; either in mark_page_accessed() or through refault-activation.
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