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Date: Mon, 15 Jun 2015 01:43:03 -0400 From: Rik van Riel <riel@...hat.com> To: Leon Romanovsky <leon@...n.nu>, Ebru Akagunduz <ebru.akagunduz@...il.com> CC: Linux-MM <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>, kirill.shutemov@...ux.intel.com, n-horiguchi@...jp.nec.com, aarcange <aarcange@...hat.com>, iamjoonsoo.kim@....com, Xiexiuqi <xiexiuqi@...wei.com>, gorcunov@...nvz.org, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Mel Gorman <mgorman@...e.de>, rientjes@...gle.com, Vlastimil Babka <vbabka@...e.cz>, aneesh.kumar@...ux.vnet.ibm.com, hughd@...gle.com, Johannes Weiner <hannes@...xchg.org>, mhocko@...e.cz, boaz@...xistor.com, raindel@...lanox.com Subject: Re: [RFC 2/3] mm: make optimistic check for swapin readahead On 06/15/2015 01:40 AM, Leon Romanovsky wrote: > On Sun, Jun 14, 2015 at 6:04 PM, Ebru Akagunduz > <ebru.akagunduz@...il.com> wrote: >> This patch makes optimistic check for swapin readahead >> to increase thp collapse rate. Before getting swapped >> out pages to memory, checks them and allows up to a >> certain number. It also prints out using tracepoints >> amount of unmapped ptes. >> >> Signed-off-by: Ebru Akagunduz <ebru.akagunduz@...il.com> >> @@ -2639,11 +2640,11 @@ static int khugepaged_scan_pmd(struct mm_struct *mm, >> { >> pmd_t *pmd; >> pte_t *pte, *_pte; >> - int ret = 0, none_or_zero = 0; >> + int ret = 0, none_or_zero = 0, unmapped = 0; >> struct page *page; >> unsigned long _address; >> spinlock_t *ptl; >> - int node = NUMA_NO_NODE; >> + int node = NUMA_NO_NODE, max_ptes_swap = HPAGE_PMD_NR/8; > Sorry for asking, my knoweldge of THP is very limited, but why did you > choose this default value? > From the discussion followed by your patch > (https://lkml.org/lkml/2015/2/27/432), I got an impression that it is > not necessary right value. I believe that Ebru's main focus for this initial version of the patch series was to get the _mechanism_ (patch 3) right, while having a fairly simple policy to drive it. Any suggestions on when it is a good idea to bring in pages from swap, and whether to treat resident-in-swap-cache pages differently from need-to-be-paged-in pages, and what other factors should be examined, are very welcome... -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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