From: Johannes Weiner <hannes@cmpxchg.org>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Andrew Morton <akpm@linux-foundation.org>,
Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/7] mm: vmscan: Convert lumpy_mode into a bitmask
Date: Thu, 2 Dec 2010 12:04:04 +0100 [thread overview]
Message-ID: <20101202110404.GW15564@cmpxchg.org> (raw)
In-Reply-To: <20101201115633.GO13268@csn.ul.ie>
On Wed, Dec 01, 2010 at 11:56:33AM +0000, Mel Gorman wrote:
> On Wed, Dec 01, 2010 at 12:21:16PM +0100, Johannes Weiner wrote:
> > On Wed, Dec 01, 2010 at 10:50:29AM +0000, Mel Gorman wrote:
> > > On Wed, Dec 01, 2010 at 11:27:32AM +0100, Johannes Weiner wrote:
> > > > On Mon, Nov 22, 2010 at 03:43:50PM +0000, Mel Gorman wrote:
> > > > > + * lumpy_mode determines how the inactive list is shrunk
> > > > > + * LUMPY_MODE_SINGLE: Reclaim only order-0 pages
> > > > > + * LUMPY_MODE_ASYNC: Do not block
> > > > > + * LUMPY_MODE_SYNC: Allow blocking e.g. call wait_on_page_writeback
> > > > > + * LUMPY_MODE_CONTIGRECLAIM: For high-order allocations, take a reference
> > > > > + * page from the LRU and reclaim all pages within a
> > > > > + * naturally aligned range
> > > >
> > > > I find those names terribly undescriptive. It also strikes me as an
> > > > odd set of flags. Can't this be represented with less?
> > > >
> > > > LUMPY_MODE_ENABLED
> > > > LUMPY_MODE_SYNC
> > > >
> > > > or, after the rename,
> > > >
> > > > RECLAIM_MODE_HIGHER = 1
> > > > RECLAIM_MODE_SYNC = 2
> > > > RECLAIM_MODE_LUMPY = 4
> > >
> > > My problem with that is you have to infer what the behaviour is from what the
> > > flags "are not" as opposed to what they are. For example, !LUMPY_MODE_SYNC
> > > implies LUMPY_MODE_ASYNC instead of specifying LUMPY_MODE_ASYNC.
> >
> > Sounds like a boolean value to me. And it shows: you never actually
> > check for RECLAIM_MODE_ASYNC in the code, you just always set it to
> > the opposite of RECLAIM_MODE_SYNC - the flag which is actually read.
>
> If you insist, the ASYNC flag can be dropped. I found it easier to flag
> what behaviour was expected than infer it.
It seems to be a matter of taste and nobody else seems to care, so I
am not insisting. Let's just keep it as it is.
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next prev parent reply other threads:[~2010-12-02 11:04 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-22 15:43 [PATCH 0/7] Use memory compaction instead of lumpy reclaim during high-order allocations V2 Mel Gorman
2010-11-22 15:43 ` [PATCH 1/7] mm: compaction: Add trace events for memory compaction activity Mel Gorman
2010-11-22 15:43 ` [PATCH 2/7] mm: vmscan: Convert lumpy_mode into a bitmask Mel Gorman
2010-12-01 10:27 ` Johannes Weiner
2010-12-01 10:50 ` Mel Gorman
2010-12-01 11:21 ` Johannes Weiner
2010-12-01 11:56 ` Mel Gorman
2010-12-02 11:04 ` Johannes Weiner [this message]
2010-12-02 12:03 ` [PATCH] mm: vmscan: Rename lumpy_mode to reclaim_mode fix Mel Gorman
2010-11-22 15:43 ` [PATCH 3/7] mm: vmscan: Reclaim order-0 and use compaction instead of lumpy reclaim Mel Gorman
2010-12-01 10:27 ` Johannes Weiner
2010-12-01 10:56 ` Mel Gorman
2010-12-01 11:32 ` Johannes Weiner
2010-11-22 15:43 ` [PATCH 4/7] mm: migration: Allow migration to operate asynchronously and avoid synchronous compaction in the faster path Mel Gorman
2010-12-01 10:28 ` Johannes Weiner
2010-11-22 15:43 ` [PATCH 5/7] mm: migration: Cleanup migrate_pages API by matching types for offlining and sync Mel Gorman
2010-12-01 10:28 ` Johannes Weiner
2010-11-22 15:43 ` [PATCH 6/7] mm: compaction: Perform a faster migration scan when migrating asynchronously Mel Gorman
2010-12-01 10:31 ` Johannes Weiner
2010-11-22 15:43 ` [PATCH 7/7] mm: vmscan: Rename lumpy_mode to reclaim_mode Mel Gorman
2010-12-01 10:34 ` Johannes Weiner
2010-11-22 16:01 ` [PATCH 0/7] Use memory compaction instead of lumpy reclaim during high-order allocations V2 Andrea Arcangeli
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