linux-kernel - Re: Re: [PATCH v6 04/14] mm/damon: Apply dynamic memory mapping changes

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Date:   Tue, 10 Mar 2020 12:53:55 +0100
From:   SeongJae Park <sjpark@...zon.com>
To:     Jonathan Cameron <Jonathan.Cameron@...wei.com>
CC:     SeongJae Park <sjpark@...zon.com>, <akpm@...ux-foundation.org>,
        "SeongJae Park" <sjpark@...zon.de>, <aarcange@...hat.com>,
        <yang.shi@...ux.alibaba.com>, <acme@...nel.org>,
        <alexander.shishkin@...ux.intel.com>, <amit@...nel.org>,
        <brendan.d.gregg@...il.com>, <brendanhiggins@...gle.com>,
        <cai@....pw>, <colin.king@...onical.com>, <corbet@....net>,
        <dwmw@...zon.com>, <jolsa@...hat.com>, <kirill@...temov.name>,
        <mark.rutland@....com>, <mgorman@...e.de>, <minchan@...nel.org>,
        <mingo@...hat.com>, <namhyung@...nel.org>, <peterz@...radead.org>,
        <rdunlap@...radead.org>, <rientjes@...gle.com>,
        <rostedt@...dmis.org>, <shuah@...nel.org>, <sj38.park@...il.com>,
        <vbabka@...e.cz>, <vdavydov.dev@...il.com>, <linux-mm@...ck.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH v6 04/14] mm/damon: Apply dynamic memory mapping changes

On Tue, 10 Mar 2020 09:00:26 +0000 Jonathan Cameron <Jonathan.Cameron@...wei.com> wrote:

> On Mon, 24 Feb 2020 13:30:37 +0100
> SeongJae Park <sjpark@...zon.com> wrote:
> 
> > From: SeongJae Park <sjpark@...zon.de>
> > 
> > Only a number of parts in the virtual address space of the processes is
> > mapped to physical memory and accessed.  Thus, tracking the unmapped
> > address regions is just wasteful.  However, tracking every memory
> > mapping change might incur an overhead.  For the reason, DAMON applies
> > the dynamic memory mapping changes to the tracking regions only for each
> > of a user-specified time interval (``regions update interval``).
> > 
> > Signed-off-by: SeongJae Park <sjpark@...zon.de>
> Trivial inline. Otherwise makes sense to me.
> 
[...]
> > +static void damon_apply_three_regions(struct damon_ctx *ctx,
> > +		struct damon_task *t, struct region bregions[3])
> > +{
> > +	struct damon_region *r, *next;
> > +	unsigned int i = 0;
> > +
> > +	/* Remove regions which isn't in the three big regions now */
> > +	damon_for_each_region_safe(r, next, t) {
> > +		for (i = 0; i < 3; i++) {
> > +			if (damon_intersect(r, &bregions[i]))
> > +				break;
> > +		}
> > +		if (i == 3)
> > +			damon_destroy_region(r);
> > +	}
> > +
> > +	/* Adjust intersecting regions to fit with the threee big regions */
> 
> three

Good eye!  Thanks for finding :)

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