From: Ning Qu <quning@google.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Wu Fengguang <fengguang.wu@intel.com>, Jan Kara <jack@suse.cz>,
Mel Gorman <mgorman@suse.de>,
linux-mm@kvack.org, Andi Kleen <ak@linux.intel.com>,
Matthew Wilcox <willy@linux.intel.com>,
Hillf Danton <dhillf@gmail.com>, Dave Hansen <dave@sr71.net>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/12] mm, thp, tmpfs: handle huge page in shmem_undo_range for truncate
Date: Wed, 16 Oct 2013 11:48:24 -0700 [thread overview]
Message-ID: <CACz4_2eAots8Xk3C8Vosqc24vs28OtsD4LecsH19MjWeQaw+2Q@mail.gmail.com> (raw)
In-Reply-To: <20131016120951.B5012E0090@blue.fi.intel.com>
Best wishes,
--
Ning Qu (曲宁) | Software Engineer | quning@google.com | +1-408-418-6066
On Wed, Oct 16, 2013 at 5:09 AM, Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> wrote:
> Ning Qu wrote:
>> > Again. Here and below ifdef is redundant: PageTransHugeCache() is zero
>> > compile-time and thp case will be optimize out.
>>
>> The problem is actually from HPAGE_CACHE_INDEX_MASK, it is marked as
>> build bug when CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE is false. So we
>> either wrap some logic inside a inline function, or we have to be like
>> this .. Or we don't treat the HPAGE_CACHE_INDEX_MASK as a build bug?
>
> HPAGE_CACHE_INDEX_MASK shouldn't be a problem.
> If it's wrapped into 'if PageTransHugeCache(page)' or similar it will be
> eliminated by compiler if thp-pc disabled and build bug will not be
> triggered.
>
Yes, you are totally right about this. I have remove all the ifdef for
CONFIG_TRANSPARENT_HUGEPAGE_PAGECACHE now. Thanks!
>>
>> >
>> > And do we really need a copy of truncate logic here? Is there a way to
>> > share code?
>> >
>> The truncate between tmpfs and general one is similar but not exactly
>> the same (no readahead), so share the whole function might not be a
>> good choice from the perspective of tmpfs? Anyway, there are other
>> similar functions in tmpfs, e.g. the one you mentioned for
>> shmem_add_to_page_cache. It is possible to share the code, I am just
>> worried it will make the logic more complicated?
>
> I think introducing thp-pc is good opportunity to refactor all these code.
>
> --
> Kirill A. Shutemov
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next prev parent reply other threads:[~2013-10-16 18:48 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-15 0:13 [PATCH 07/12] mm, thp, tmpfs: handle huge page in shmem_undo_range for truncate Ning Qu
2013-10-15 11:01 ` Kirill A. Shutemov
2013-10-15 18:48 ` Ning Qu
2013-10-16 12:09 ` Kirill A. Shutemov
2013-10-16 18:48 ` Ning Qu [this message]
2013-10-17 20:58 ` Ning Qu
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