Date: Tue, 30 Dec 2008 08:52:02 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Andrew Morton <akpm@linux-foundation.org>,
       "H. Peter Anvin" <hpa@zytor.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/14] kmemleak: Add the base support
Message-ID: <20081230075202.GB5482@elte.hu>
References: <20081219181255.7778.52219.stgit@pc1117.cambridge.arm.com> <20081219181302.7778.15966.stgit@pc1117.cambridge.arm.com> <20081229162314.1cc7a549.akpm@linux-foundation.org> <20081230073807.GA2455@elte.hu> <20081229234447.41c3c1b1.akpm@linux-foundation.org>
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* Andrew Morton <akpm@linux-foundation.org> wrote:

> On Tue, 30 Dec 2008 08:38:07 +0100 Ingo Molnar <mingo@elte.hu> wrote:
> 
> > * Andrew Morton <akpm@linux-foundation.org> wrote:
> > 
> > > > +/*
> > > > + * Stop the automatic memory scanning thread. This function must be called
> > > > + * with the kmemleak_mutex held.
> > > > + */
> > > > +void stop_scan_thread(void)
> > > > +{
> > > > +	if (scan_thread) {
> > > > +		kthread_stop(scan_thread);
> > > > +		scan_thread = NULL;
> > > > +	}
> > > > +}
> > > 
> > > so... why do we need a kernel thread?
> > > 
> > > We could have (for the sake of argument) a sys_kmemleak_scan() which 
> > > does a single scan then returns.  Or something like that.  That way, 
> > > userspace directly gets to set the scanning frequency, thread priority, 
> > > etc.
> > 
> > thread priority of a kernel thread can be set anyway. Kernel threads tend 
> > to be better for such simple things because we can control all aspects, 
> > start them automatically so that test setups catch it (without needing any 
> > userspace component), etc.
> > 
> 
> yeah yeah, userspace is too hard for kernel programmers, so we put our 
> applications, English-only pretty-printers etc into the kernel.  It's a 
> broken record.

above a certain threshold i think we need to start thinking about merging 
klibc, and moving some key system applications into the kernel source 
proper (those which closely depend on the kernel version anyway and need 
to be updated together).

	Ingo
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