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From: Robin Holt <holt@sgi.com>
To: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>
Cc: Robin Holt <holt@sgi.com>, Nate Zimmer <nzimmer@sgi.com>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux MM <linux-mm@kvack.org>, Rob Landley <rob@landley.net>,
	Mike Travis <travis@sgi.com>,
	Daniel J Blueman <daniel@numascale-asia.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Yinghai Lu <yinghai@kernel.org>, Mel Gorman <mgorman@suse.de>
Subject: Re: [RFC 0/4] Transparent on-demand struct page initialization embedded in the buddy allocator
Date: Mon, 15 Jul 2013 10:00:40 -0500	[thread overview]
Message-ID: <20130715150040.GA3421@sgi.com> (raw)
In-Reply-To: <1373594635-131067-1-git-send-email-holt@sgi.com>

On Thu, Jul 11, 2013 at 09:03:51PM -0500, Robin Holt wrote:
> We have been working on this since we returned from shutdown and have
> something to discuss now.  We restricted ourselves to 2MiB initialization
> to keep the patch set a little smaller and more clear.
> 
> First, I think I want to propose getting rid of the page flag.  If I knew
> of a concrete way to determine that the page has not been initialized,
> this patch series would look different.  If there is no definitive
> way to determine that the struct page has been initialized aside from
> checking the entire page struct is zero, then I think I would suggest
> we change the page flag to indicate the page has been initialized.

Ingo or HPA,

Did I implement this wrong or is there a way to get rid of the page flag
which is not going to impact normal operation?  I don't want to put too
much more effort into this until I know we are stuck going this direction.
Currently, the expand() function has a relatively expensive checked
against the 2MiB aligned pfn's struct page.  I do not know of a way to
eliminate that check against the other page as the first reference we
see for a page is in the middle of that 2MiB aligned range.

To identify this as an area of concern, we had booted with a simulator,
setting watch points on the struct page array region once the
Uninitialized flag was set and maintaining that until it was cleared.

Thanks,
Robin

  parent reply	other threads:[~2013-07-15 15:00 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-12  2:03 [RFC 0/4] Transparent on-demand struct page initialization embedded in the buddy allocator Robin Holt
2013-07-12  2:03 ` [RFC 1/4] memblock: Introduce a for_each_reserved_mem_region iterator Robin Holt
2013-07-12  2:03 ` [RFC 2/4] Have __free_pages_memory() free in larger chunks Robin Holt
2013-07-12  7:45   ` Robin Holt
2013-07-13  3:08     ` Yinghai Lu
2013-07-16 13:02   ` Sam Ben
2013-07-23 15:32     ` Johannes Weiner
2013-07-12  2:03 ` [RFC 3/4] Seperate page initialization into a separate function Robin Holt
2013-07-13  3:06   ` Yinghai Lu
2013-07-15  3:19     ` Robin Holt
2013-07-12  2:03 ` [RFC 4/4] Sparse initialization of struct page array Robin Holt
2013-07-13  4:19   ` Yinghai Lu
2013-07-13  4:39     ` H. Peter Anvin
2013-07-13  5:31       ` Yinghai Lu
2013-07-13  5:38         ` H. Peter Anvin
2013-07-15 14:08         ` Nathan Zimmer
2013-07-15 17:45     ` Nathan Zimmer
2013-07-15 17:54       ` H. Peter Anvin
2013-07-15 18:26         ` Robin Holt
2013-07-15 18:29           ` H. Peter Anvin
2013-07-23  8:32             ` Ingo Molnar
2013-07-23 11:09               ` Robin Holt
2013-07-23 11:15                 ` Robin Holt
2013-07-23 11:41                   ` Robin Holt
2013-07-23 11:50                     ` Robin Holt
2013-07-16 10:26     ` Robin Holt
2013-07-25  2:25     ` Robin Holt
2013-07-25 12:50       ` Yinghai Lu
2013-07-25 13:42         ` Robin Holt
2013-07-25 13:52           ` Yinghai Lu
2013-07-15 21:30   ` Andrew Morton
2013-07-16 10:38     ` Robin Holt
2013-07-12  8:27 ` [RFC 0/4] Transparent on-demand struct page initialization embedded in the buddy allocator Ingo Molnar
2013-07-12  8:47   ` boot tracing Borislav Petkov
2013-07-12  8:53     ` Ingo Molnar
2013-07-15  1:38       ` Sam Ben
2013-07-23  8:18         ` Ingo Molnar
2013-07-12  9:19   ` [RFC 0/4] Transparent on-demand struct page initialization embedded in the buddy allocator Robert Richter
2013-07-15 15:16   ` Robin Holt
2013-07-16  8:55   ` Joonsoo Kim
2013-07-16  9:08     ` Borislav Petkov
2013-07-23  8:20       ` Ingo Molnar
2013-07-15 15:00 ` Robin Holt [this message]
2013-07-17  5:17 ` Sam Ben
2013-07-17  9:30   ` Robin Holt
2013-07-19 23:51     ` Yinghai Lu
2013-07-22  6:13       ` Robin Holt
2013-08-02 17:44 ` [RFC v2 0/5] " Nathan Zimmer
2013-08-02 17:44   ` [RFC v2 1/5] memblock: Introduce a for_each_reserved_mem_region iterator Nathan Zimmer
2013-08-02 17:44   ` [RFC v2 2/5] Have __free_pages_memory() free in larger chunks Nathan Zimmer
2013-08-02 17:44   ` [RFC v2 3/5] Move page initialization into a separate function Nathan Zimmer
2013-08-02 17:44   ` [RFC v2 4/5] Only set page reserved in the memblock region Nathan Zimmer
2013-08-03 20:04     ` Nathan Zimmer
2013-08-02 17:44   ` [RFC v2 5/5] Sparse initialization of struct page array Nathan Zimmer
2013-08-05  9:58   ` [RFC v2 0/5] Transparent on-demand struct page initialization embedded in the buddy allocator Ingo Molnar
2013-08-12 21:54   ` [RFC v3 " Nathan Zimmer
2013-08-12 21:54     ` [RFC v3 1/5] memblock: Introduce a for_each_reserved_mem_region iterator Nathan Zimmer
2013-08-12 21:54     ` [RFC v3 2/5] Have __free_pages_memory() free in larger chunks Nathan Zimmer
2013-08-12 21:54     ` [RFC v3 3/5] Move page initialization into a separate function Nathan Zimmer
2013-08-12 21:54     ` [RFC v3 4/5] Only set page reserved in the memblock region Nathan Zimmer
2013-08-12 21:54     ` [RFC v3 5/5] Sparse initialization of struct page array Nathan Zimmer
2013-08-13 10:58     ` [RFC v3 0/5] Transparent on-demand struct page initialization embedded in the buddy allocator Ingo Molnar
2013-08-13 17:09     ` Linus Torvalds
2013-08-13 17:23       ` H. Peter Anvin
2013-08-13 17:33       ` Mike Travis
2013-08-13 17:51         ` Linus Torvalds
2013-08-13 18:04           ` Mike Travis
2013-08-13 19:06             ` Mike Travis
2013-08-13 20:24               ` Yinghai Lu
2013-08-13 20:37                 ` Mike Travis
2013-08-13 21:35             ` Nathan Zimmer
2013-08-13 23:10           ` Nathan Zimmer
2013-08-13 23:55             ` Linus Torvalds
2013-08-14 11:27               ` Ingo Molnar
2013-08-14 11:05           ` Ingo Molnar
2013-08-14 22:15             ` Nathan Zimmer
2013-08-16 16:36     ` Dave Hansen

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