Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1165029

Re: [RFC 2/3] mm: make optimistic check for swapin readahead

Show all headers | View raw

On 06/15/2015 01:40 AM, Leon Romanovsky wrote:
> On Sun, Jun 14, 2015 at 6:04 PM, Ebru Akagunduz
> <ebru.akagunduz@gmail.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@gmail.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@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [RFC 2/3] mm: make optimistic check for swapin readahead Rik van Riel <riel@redhat.com> - 2015-06-15 07:50 +0200
  Re: [RFC 2/3] mm: make optimistic check for swapin readahead Leon Romanovsky <leon@leon.nu> - 2015-06-15 08:10 +0200
    Re: [RFC 2/3] mm: make optimistic check for swapin readahead Rik van Riel <riel@redhat.com> - 2015-06-15 08:40 +0200

csiph-web