From: Andrea Righi <andrea.righi@canonical.com>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan@kernel.org>,
Anchal Agarwal <anchalag@amazon.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm: swap: use fixed-size readahead during swapoff
Date: Wed, 15 Apr 2020 11:19:48 +0200 [thread overview]
Message-ID: <20200415091948.GH810380@xps-13> (raw)
In-Reply-To: <87imi1yz07.fsf@yhuang-dev.intel.com>
On Wed, Apr 15, 2020 at 03:44:08PM +0800, Huang, Ying wrote:
> Andrea Righi <andrea.righi@canonical.com> writes:
>
> > mm/swapfile.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/swapfile.c b/mm/swapfile.c
> > index 9fd47e6f7a86..cb9eb517178d 100644
> > --- a/mm/swapfile.c
> > +++ b/mm/swapfile.c
> > @@ -1944,7 +1944,9 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
> > vmf.pmd = pmd;
> > last_ra = atomic_read(&last_readahead_pages);
> > atomic_set(&swapin_readahead_hits, last_ra);
>
> You need to remove the above 2 lines firstly.
Meh... too much enthusiasm, and I definitely need more coffee this
morning. Here's the right patch applied:
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 5871a2aa86a5..8b38441b66fa 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1940,7 +1940,9 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
vmf.vma = vma;
vmf.address = addr;
vmf.pmd = pmd;
- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf);
+ page = lookup_swap_cache(entry, vma, addr);
+ if (!page)
+ page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf);
if (!page) {
if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD)
goto try_next;
And following the right results:
r::swapin_nr_pages(unsigned long offset):unsigned long:$retval
COUNT EVENT
1618 $retval = 1
4960 $retval = 2
41315 $retval = 4
103521 $retval = 8
swapoff time: 12.19s
So, not as good as the fixed-size readahead, but it's definitely an
improvement, considering that the swapoff time is ~22s without this
patch applied.
I think this change can be a simple and reasonable compromise.
Thanks again and sorry for the noise,
-Andrea
next prev parent reply other threads:[~2020-04-15 9:19 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-13 11:18 [PATCH v2] mm: swap: use fixed-size readahead during swapoff Andrea Righi
2020-04-13 13:00 ` Huang, Ying
2020-04-13 13:31 ` Andrea Righi
2020-04-14 1:31 ` Huang, Ying
2020-04-14 13:05 ` Andrea Righi
2020-04-15 2:37 ` Huang, Ying
2020-04-15 7:32 ` Andrea Righi
2020-04-15 7:44 ` Huang, Ying
2020-04-15 9:19 ` Andrea Righi [this message]
2020-04-16 0:44 ` Huang, Ying
2020-04-15 12:00 ` Andrea Righi
2020-04-16 0:41 ` Huang, Ying
2020-04-16 17:21 ` Andrea Righi
2020-04-13 13:13 ` Huang, Ying
2020-04-13 13:26 ` Andrea Righi
2020-04-14 1:45 ` Huang, Ying
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200415091948.GH810380@xps-13 \
--to=andrea.righi@canonical.com \
--cc=akpm@linux-foundation.org \
--cc=anchalag@amazon.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=minchan@kernel.org \
--cc=ying.huang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).