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Message-ID: <ZbQHWf0Hh04OwoZx@casper.infradead.org>
Date: Fri, 26 Jan 2024 19:26:17 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Luis Chamberlain <mcgrof@...nel.org>
Cc: kernel test robot <oliver.sang@...el.com>,
Daniel Gomez <da.gomez@...sung.com>, oe-lkp@...ts.linux.dev,
lkp@...el.com, linux-kernel@...r.kernel.org,
"gost.dev@...sung.com" <gost.dev@...sung.com>,
Pankaj Raghav <p.raghav@...sung.com>
Subject: Re: [PATCH 1/2] test_xarray: add tests for advanced multi-index use
On Fri, Jan 26, 2024 at 11:12:03AM -0800, Luis Chamberlain wrote:
> On Fri, Nov 17, 2023 at 01:01:18PM -0800, Luis Chamberlain wrote:
> > On Fri, Nov 17, 2023 at 08:58:05PM +0000, Matthew Wilcox wrote:
> > > On Fri, Nov 17, 2023 at 12:54:09PM -0800, Luis Chamberlain wrote:
> > > > +/*
> > > > + * Can be used in contexts which busy loop on large number of entries but can
> > > > + * sleep and timing is if no importance to test correctness.
> > > > + */
> > > > +#define XA_BUG_ON_RELAX(xa, x) do { \
> > > > + if ((tests_run % 1000) == 0) \
> > > > + schedule(); \
> > > > + XA_BUG_ON(xa, x); \
> > > > +} while (0)
> > >
> > > That is awful. Please don't do that. You're mixing two completely
> > > unrelated thing into the same macro, which makes no sense. Not only
> > > that, it's a macro which refers to something in the containing
> > > environment that isn't a paramter to the macro.
> >
> > I figured you'd puke. Would you prefer I just open code the check on the loop
> > though? I'm sure another alternative is we *not care* about these
> > overloaded systems running the test. What would you prefer?
>
> OK without any particular preferences outlined this is what I have,
> splitting the two contexts and making the busy loop fix clearer.
>
> +#define XA_BUSY_LOOP_RELAX(xa, x) do { \
> + if ((i % 1000) == 0) \
> + schedule(); \
> +} while (0)
> +
> +/*
> + * Can be used in contexts which busy loop on large number of entries but can
> + * sleep and timing is if no importance to test correctness.
> + */
> +#define XA_BUG_ON_RELAX(i, xa, x) do { \
> + XA_BUSY_LOOP_RELAX(i); \
> + XA_BUG_ON(xa, x); \
> +} while (0)
No. XA_BUG_ON_RELAX is not OK. Really.
We have a perfectly good system for "relaxing":
xas_for_each_marked(&xas, page, end, PAGECACHE_TAG_DIRTY) {
xas_set_mark(&xas, PAGECACHE_TAG_TOWRITE);
if (++tagged % XA_CHECK_SCHED)
continue;
xas_pause(&xas);
xas_unlock_irq(&xas);
cond_resched();
xas_lock_irq(&xas);
}
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