From: Minchan Kim <minchan@kernel.org>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huang, Ying" <ying.huang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrea Arcangeli <aarcange@redhat.com>,
Ebru Akagunduz <ebru.akagunduz@gmail.com>,
Michal Hocko <mhocko@kernel.org>, Tejun Heo <tj@kernel.org>,
Hugh Dickins <hughd@google.com>, Shaohua Li <shli@kernel.org>,
Rik van Riel <riel@redhat.com>,
cgroups@vger.kernel.org
Subject: Re: [PATCH -mm -v10 1/3] mm, THP, swap: Delay splitting THP during swap out
Date: Thu, 11 May 2017 08:25:56 +0900 [thread overview]
Message-ID: <20170510232556.GA26521@bbox> (raw)
In-Reply-To: <20170510135654.GD17121@cmpxchg.org>
On Wed, May 10, 2017 at 09:56:54AM -0400, Johannes Weiner wrote:
> Hi Michan,
>
> On Tue, May 02, 2017 at 08:53:32AM +0900, Minchan Kim wrote:
> > @@ -1144,7 +1144,7 @@ void swap_free(swp_entry_t entry)
> > /*
> > * Called after dropping swapcache to decrease refcnt to swap entries.
> > */
> > -void swapcache_free(swp_entry_t entry)
> > +void __swapcache_free(swp_entry_t entry)
> > {
> > struct swap_info_struct *p;
> >
> > @@ -1156,7 +1156,7 @@ void swapcache_free(swp_entry_t entry)
> > }
> >
> > #ifdef CONFIG_THP_SWAP
> > -void swapcache_free_cluster(swp_entry_t entry)
> > +void __swapcache_free_cluster(swp_entry_t entry)
> > {
> > unsigned long offset = swp_offset(entry);
> > unsigned long idx = offset / SWAPFILE_CLUSTER;
> > @@ -1182,6 +1182,14 @@ void swapcache_free_cluster(swp_entry_t entry)
> > }
> > #endif /* CONFIG_THP_SWAP */
> >
> > +void swapcache_free(struct page *page, swp_entry_t entry)
> > +{
> > + if (!PageTransHuge(page))
> > + __swapcache_free(entry);
> > + else
> > + __swapcache_free_cluster(entry);
> > +}
>
> I don't think this is cleaner :/
>
> On your second patch:
>
> > @@ -1125,8 +1125,28 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > !PageSwapCache(page)) {
> > if (!(sc->gfp_mask & __GFP_IO))
> > goto keep_locked;
> > - if (!add_to_swap(page, page_list))
> > +swap_retry:
> > + /*
> > + * Retry after split if we fail to allocate
> > + * swap space of a THP.
> > + */
> > + if (!add_to_swap(page)) {
> > + if (!PageTransHuge(page) ||
> > + split_huge_page_to_list(page, page_list))
> > + goto activate_locked;
> > + goto swap_retry;
> > + }
>
> This is definitely better.
Thanks.
>
> However, I think it'd be cleaner without the label here:
>
> if (!add_to_swap(page)) {
> if (!PageTransHuge(page))
> goto activate_locked;
> /* Split THP and swap individual base pages */
> if (split_huge_page_to_list(page, page_list))
> goto activate_locked;
> if (!add_to_swap(page))
> goto activate_locked;
Yes.
> }
>
> > + /*
> > + * Got swap space successfully. But unfortunately,
> > + * we don't support a THP page writeout so split it.
> > + */
> > + if (PageTransHuge(page) &&
> > + split_huge_page_to_list(page, page_list)) {
> > + delete_from_swap_cache(page);
> > goto activate_locked;
> > + }
>
> Pulling this out of add_to_swap() is an improvement for sure. Add an
> XXX: before that "we don't support THP writes" comment for good
> measure :)
Sure.
It could be a separate patch which makes add_to_swap clean via
removing page_list argument but I hope Huang take/fold it when he
resend it because it would be more important with THP swap.
Thanks.
next prev parent reply other threads:[~2017-05-10 23:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 12:56 [PATCH -mm -v10 0/3] THP swap: Delay splitting THP during swapping out Huang, Ying
2017-04-25 12:56 ` [PATCH -mm -v10 1/3] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
2017-04-27 5:31 ` Minchan Kim
2017-04-27 7:12 ` Huang, Ying
2017-04-27 13:37 ` Johannes Weiner
2017-04-28 8:40 ` Minchan Kim
2017-04-28 12:21 ` Huang, Ying
2017-05-10 1:03 ` Minchan Kim
2017-05-01 10:44 ` Johannes Weiner
2017-05-01 23:53 ` Minchan Kim
2017-05-10 13:56 ` Johannes Weiner
2017-05-10 23:25 ` Minchan Kim [this message]
2017-05-11 0:50 ` Huang, Ying
2017-05-11 4:31 ` Minchan Kim
2017-05-12 2:21 ` [PATCH 1/2] mm: swap: unify swap slot free functions to put_swap_page Minchan Kim
2017-05-12 2:21 ` [PATCH 2/2] mm: swap: move anonymous THP split logic to vmscan Minchan Kim
2017-05-12 16:48 ` Johannes Weiner
2017-05-12 16:47 ` [PATCH 1/2] mm: swap: unify swap slot free functions to put_swap_page Johannes Weiner
2017-05-11 1:22 ` [PATCH -mm -v10 1/3] mm, THP, swap: Delay splitting THP during swap out Minchan Kim
2017-05-11 10:40 ` Johannes Weiner
2017-05-12 1:34 ` Minchan Kim
2017-04-25 12:56 ` [PATCH -mm -v10 2/3] mm, THP, swap: Check whether THP can be split firstly Huang, Ying
2017-04-25 21:43 ` Johannes Weiner
2017-04-25 12:56 ` [PATCH -mm -v10 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map Huang, Ying
2017-04-25 21:46 ` Johannes Weiner
2017-04-28 13:16 ` Kirill A. Shutemov
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