Messages in this thread |  | | | Date | Thu, 10 Nov 2011 18:31:05 -0800 (PST) | | From | Hugh Dickins <> | | Subject | Re: [PATCH v2] mm: add free_hot_cold_page_list helper |
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On Tue, 1 Nov 2011, Konstantin Khlebnikov wrote:
> This patch adds helper free_hot_cold_page_list() to free list of 0-order pages. > It frees pages directly from the list without temporary page-vector. > It also calls trace_mm_pagevec_free() to simulate pagevec_free() behaviour.
Sorry for not speaking up sooner, but I do like this patch very much (and I'm content with your trace compatibility choice - whatever).
Not so much in itself, but because it then allows a further patch (mainly to mm/vmscan.c) to remove two levels of pagevec, reducing its deepest stack by around 240 bytes.
I have that patch, but keep putting off sending it in, because I want to show a reclaim stack overflow that it prevents, but the new avoidance of writeback in direct reclaim makes that harder to demonstrate. Damn!
One question on your patch: where you have release_pages() doing > + list_add_tail(&page->lru, &pages_to_free);
That seems reasonable, but given that __pagevec_free() proceeds by while (--i >= 0) { , starting from the far end of the pagevec (the most recently added struct page, the most likely to be hot), wouldn't you reproduce existing behaviour more accurately by a simple list_add()? Or have I got that back to front? If so, a comment on the list_add_tail() would help me to remember why - thanks.
Hugh
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