From: Matthew Wilcox <willy@infradead.org>
To: Ira Weiny <ira.weiny@intel.com>
Cc: "Huang, Ying" <ying.huang@intel.com>,
Yang Shi <yang.shi@linux.alibaba.com>,
hannes@cmpxchg.org, mhocko@suse.com, mgorman@techsingularity.net,
kirill.shutemov@linux.intel.com, hughd@google.com,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: vmscan: correct nr_reclaimed for THP
Date: Fri, 10 May 2019 16:06:20 -0700 [thread overview]
Message-ID: <20190510230620.GA12158@bombadil.infradead.org> (raw)
In-Reply-To: <20190510225456.GA13529@iweiny-DESK2.sc.intel.com>
On Fri, May 10, 2019 at 03:54:56PM -0700, Ira Weiny wrote:
> On Fri, May 10, 2019 at 09:36:12AM -0700, Matthew Wilcox wrote:
> > On Fri, May 10, 2019 at 10:12:40AM +0800, Huang, Ying wrote:
> > > > + nr_reclaimed += (1 << compound_order(page));
> > >
> > > How about to change this to
> > >
> > >
> > > nr_reclaimed += hpage_nr_pages(page);
> >
> > Please don't. That embeds the knowledge that we can only swap out either
> > normal pages or THP sized pages. I'm trying to make the VM capable of
> > supporting arbitrary-order pages, and this would be just one more place
> > to fix.
> >
> > I'm sympathetic to the "self documenting" argument. My current tree has
> > a patch in it:
> >
> > mm: Introduce compound_nr
> >
> > Replace 1 << compound_order(page) with compound_nr(page). Minor
> > improvements in readability.
> >
> > It goes along with this patch:
> >
> > mm: Introduce page_size()
> >
> > It's unnecessarily hard to find out the size of a potentially huge page.
> > Replace 'PAGE_SIZE << compound_order(page)' with page_size(page).
> >
> > Better suggestions on naming gratefully received. I'm more happy with
> > page_size() than I am with compound_nr(). page_nr() gives the wrong
> > impression; page_count() isn't great either.
>
> Stupid question : what does 'nr' stand for?
NumbeR. It's relatively common argot in the Linux kernel (as you can
see from the earlier example ...
> > > nr_reclaimed += hpage_nr_pages(page);
willy@bobo:~/kernel/xarray-2$ git grep -w nr mm |wc -l
388
willy@bobo:~/kernel/xarray-2$ git grep -w nr fs |wc -l
1067
next prev parent reply other threads:[~2019-05-10 23:06 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-10 0:16 [PATCH] mm: vmscan: correct nr_reclaimed for THP Yang Shi
2019-05-10 0:39 ` Shakeel Butt
2019-05-10 2:12 ` Huang, Ying
2019-05-10 2:25 ` Yang Shi
2019-05-10 3:03 ` Huang, Ying
2019-05-10 4:33 ` William Kucharski
2019-05-10 15:48 ` Yang Shi
2019-05-10 15:41 ` Yang Shi
2019-05-10 16:36 ` Matthew Wilcox
2019-05-10 16:50 ` Yang Shi
2019-05-10 16:52 ` Matthew Wilcox
2019-05-10 16:54 ` Yang Shi
2019-05-10 22:54 ` Ira Weiny
2019-05-10 23:06 ` Matthew Wilcox [this message]
2019-05-11 4:09 ` Yafang Shao
2019-05-11 22:33 ` William Kucharski
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