From: Johannes Weiner <hannes@cmpxchg.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
William Kucharski <william.kucharski@oracle.com>,
Jani Nikula <jani.nikula@linux.intel.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Chris Wilson <chris@chris-wilson.co.uk>,
Matthew Auld <matthew.auld@intel.com>,
Huang Ying <ying.huang@intel.com>,
intel-gfx@lists.freedesktop.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/8] mm: Use find_get_swap_page in memcontrol
Date: Wed, 26 Aug 2020 12:26:47 -0400 [thread overview]
Message-ID: <20200826162647.GA995045@cmpxchg.org> (raw)
In-Reply-To: <20200826145414.GS17456@casper.infradead.org>
On Wed, Aug 26, 2020 at 03:54:14PM +0100, Matthew Wilcox wrote:
> On Wed, Aug 26, 2020 at 10:20:02AM -0400, Johannes Weiner wrote:
> > On Wed, Aug 19, 2020 at 07:48:44PM +0100, Matthew Wilcox (Oracle) wrote:
> > > + return find_get_swap_page(vma->vm_file->f_mapping,
> > > + linear_page_index(vma, addr));
> >
> > The refactor makes sense to me, but the name is confusing. We're not
> > looking for a swap page, we're primarily looking for a file page in
> > the page cache mapping that's handed in. Only in the special case
> > where it's a shmem mapping and there is a swap entry do we consult the
> > auxiliary swap cache.
> >
> > How about find_get_page_or_swapcache()? find_get_page_shmemswap()?
> > Maybe you have a better idea. It's a fairly specialized operation that
> > isn't widely used, so a longer name isn't a bad thing IMO.
>
> Yeah, I had trouble with the naming here too.
>
> get_page_even_from_swap()
> find_get_shmem_page()
>
> or maybe refactor the whole thing:
>
> struct page *page = find_get_entry(mapping, index);
> page = find_swap_page(mapping, page);
>
> struct page *find_swap_page(struct address_space *mapping, struct page *page)
> {
> swp_entry_t swp;
> struct swap_info_struct *si;
>
> if (!xa_is_value(page))
> return page;
> if (!shmem_mapping(mapping))
> return NULL;
>
> ...
> }
Yeah, I like the idea of two lookups if we can't find a good name for
the operation that combines them. I'd just bubble the control flow
that links them up to the callsite - that still seems plenty compact
for two callsites, and keeps all the shmem magic in shmem code:
page = find_get_entry(mapping, index);
if (xa_is_value(page))
if (shmem_mapping(mapping))
page = lookup_shmem_swap_cache(page);
else
page = NULL;
So close to making radix_to_swp_entry() & co. private to shmem.c, too
- if it weren't for force_shm_swapin_readahead(). Ah well.
next prev parent reply other threads:[~2020-08-26 16:28 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-19 18:48 [PATCH 0/8] Return head pages from find_get_entry and find_lock_entry Matthew Wilcox (Oracle)
2020-08-19 18:48 ` [PATCH 1/8] mm: Factor find_get_swap_page out of mincore_page Matthew Wilcox (Oracle)
2020-08-19 19:21 ` Matthew Wilcox
2020-08-19 18:48 ` [PATCH 2/8] mm: Use find_get_swap_page in memcontrol Matthew Wilcox (Oracle)
2020-08-26 14:20 ` Johannes Weiner
2020-08-26 14:54 ` Matthew Wilcox
2020-08-26 16:26 ` Johannes Weiner [this message]
2020-08-27 12:59 ` Matthew Wilcox
2020-08-27 14:22 ` Johannes Weiner
2020-08-19 18:48 ` [PATCH 3/8] mm: Optimise madvise WILLNEED Matthew Wilcox (Oracle)
2020-08-26 14:23 ` Johannes Weiner
2020-08-19 18:48 ` [PATCH 4/8] proc: Optimise smaps for shmem entries Matthew Wilcox (Oracle)
2020-08-26 14:24 ` Johannes Weiner
2020-08-19 18:48 ` [PATCH 5/8] i915: Use find_lock_page instead of find_lock_entry Matthew Wilcox (Oracle)
2020-08-26 14:27 ` Johannes Weiner
2020-08-19 18:48 ` [PATCH 6/8] mm: Convert find_get_entry to return the head page Matthew Wilcox (Oracle)
2020-08-26 15:09 ` Johannes Weiner
2020-08-26 15:48 ` Matthew Wilcox
2020-08-19 18:48 ` [PATCH 7/8] mm: Return head page from find_lock_entry Matthew Wilcox (Oracle)
2020-08-19 18:48 ` [PATCH 8/8] mm: Hoist find_subpage call further up in pagecache_get_page Matthew Wilcox (Oracle)
2020-08-21 17:37 ` [PATCH 0/8] Return head pages from find_get_entry and find_lock_entry William Kucharski
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