From: Michal Hocko <mhocko@kernel.org>
To: William Kucharski <william.kucharski@oracle.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Dave Hansen <dave.hansen@linux.intel.com>,
Song Liu <songliubraving@fb.com>,
Bob Kasten <robert.a.kasten@intel.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Chad Mynhier <chad.mynhier@oracle.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Johannes Weiner <jweiner@fb.com>,
Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v5 1/2] mm: Allow the page cache to allocate large pages
Date: Wed, 4 Sep 2019 10:28:05 +0200 [thread overview]
Message-ID: <20190904082805.GJ3838@dhcp22.suse.cz> (raw)
In-Reply-To: <68E123A9-22A8-40ED-B2ED-897FC02D7D75@oracle.com>
On Tue 03-09-19 21:30:30, William Kucharski wrote:
>
>
> > On Sep 3, 2019, at 5:57 AM, Michal Hocko <mhocko@kernel.org> wrote:
> >
> > On Mon 02-09-19 03:23:40, William Kucharski wrote:
> >> Add an 'order' argument to __page_cache_alloc() and
> >> do_read_cache_page(). Ensure the allocated pages are compound pages.
> >
> > Why do we need to touch all the existing callers and change them to use
> > order 0 when none is actually converted to a different order? This just
> > seem to add a lot of code churn without a good reason. If anything I
> > would simply add __page_cache_alloc_order and make __page_cache_alloc
> > call it with order 0 argument.
>
> All the EXISTING code in patch [1/2] is changed to call it with an order
> of 0, as you would expect.
>
> However, new code in part [2/2] of the patch calls it with an order of
> HPAGE_PMD_ORDER, as it seems cleaner to have those routines operate on
> a page, regardless of the order of the page desired.
>
> I certainly can change this as you request, but once again the question
> is whether "page" should MEAN "page" regardless of the order desired,
> or whether the assumption will always be "page" means base PAGESIZE.
>
> Either approach works, but what is the semantic we want going forward?
I do not have anything against handling page as compound, if that is the
question. All I was interested in whether adding a new helper to
_allocate_ the comound page wouldn't be easier than touching all
existing __page_cache_alloc users.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-09-04 8:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-02 9:23 [PATCH v5 0/2] mm,thp: Add filemap_huge_fault() for THP William Kucharski
2019-09-02 9:23 ` [PATCH v5 1/2] mm: Allow the page cache to allocate large pages William Kucharski
2019-09-03 11:57 ` Michal Hocko
2019-09-03 12:11 ` Matthew Wilcox
2019-09-03 12:19 ` Michal Hocko
2019-09-03 16:28 ` Matthew Wilcox
2019-09-03 19:18 ` Michal Hocko
2019-09-04 3:30 ` William Kucharski
2019-09-04 8:28 ` Michal Hocko [this message]
2019-09-02 9:23 ` [PATCH v5 2/2] mm,thp: Add experimental config option RO_EXEC_FILEMAP_HUGE_FAULT_THP William Kucharski
2019-09-03 12:14 ` Michal Hocko
2019-09-03 12:22 ` Matthew Wilcox
2019-09-03 12:51 ` Michal Hocko
2019-09-03 15:10 ` Matthew Wilcox
2019-09-03 19:15 ` Michal Hocko
2019-09-04 3:23 ` William Kucharski
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