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Message-ID: <3f250c710503010744390391e2@mail.gmail.com>
Date: Tue, 1 Mar 2005 11:44:22 -0400
From: Mauricio Lin <mauriciolin@gmail.com>
Reply-To: Mauricio Lin <mauriciolin@gmail.com>
To: Hugh Dickins <hugh@veritas.com>
Subject: Re: [PATCH] A new entry for /proc
Cc: Andrew Morton <akpm@osdl.org>, wli@holomorphy.com,
       linux-kernel@vger.kernel.org, rrebel@whenu.com,
       marcelo.tosatti@cyclades.com, nickpiggin@yahoo.com.au
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Hi,

Here are some values about the experiments. The values are the elapsed
real time used by the process, in seconds. Each row corresponds to
10000 cat /proc/pid/smaps command.

Old smaps
19.41
19.31
21.38
20.16

New smaps
16.82
16.75
16.75
16.79


BR,

Mauricio Lin.

On Tue, 1 Mar 2005 10:17:56 -0400, Mauricio Lin <mauriciolin@gmail.com> wrote:
> Well,
> 
> It is working better now. You are right Hugh. Now the new version is
> faster than the old one. I removed the struct page and its related
> function.
> 
> Thanks,
> 
> BR,
> 
> Mauricio Lin.
> 
> On Tue, 1 Mar 2005 04:08:15 -0400, Mauricio Lin <mauriciolin@gmail.com> wrote:
> > On Mon, 28 Feb 2005 20:41:31 +0000 (GMT), Hugh Dickins <hugh@veritas.com> wrote:
> > > On Mon, 28 Feb 2005, Mauricio Lin wrote:
> > > >
> > > > Now I am testing with /proc/pid/smaps and the values are showing that
> > > > the old one is faster than the new one. So I will keep using the old
> > > > smaps version.
> > >
> > > Sorry, I don't have time for more than the briefest look.
> > >
> > > It appears that your old resident_mem_size method is just checking
> > > pte_present, whereas your new smaps_pte_range method is also doing
> > > pte_page (yet no prior check for pfn_valid: wrong) and checking
> > > !PageReserved i.e. accessing the struct page corresponding to each
> > > pte.  So it's not a fair comparison, your new method is accessing
> > > many more cachelines than your old method.
> > >
> > > Though it's correct to check pfn_valid and !PageReserved to get the
> > > same total rss as would be reported elsewhere, I'd suggest that it's
> > > really not worth the overhead of those struct page accesses: just
> > > stick with the pte_present test.
> > So, I can remove the PageReserved macro without no problems, right?
> >
> >
> > >
> > > Your smaps_pte_range is missing pte_unmap?
> > Yes, but I already fixed this problem.  Paul Mundt has checked the
> > unmap missing.
> >
> > Thanks,
> >
> > Let me perform new experiments now.
> >
> > BR,
> >
> > Mauricio Lin.
> >
>
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