From: Michael Neuling <mikey@neuling.org>
To: Michael Ellerman <michael@ellerman.id.au>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] powerpc: Dynamically allocate pacas
Date: Wed, 27 Jan 2010 17:29:36 +1030 [thread overview]
Message-ID: <4389.1264575576@neuling.org> (raw)
In-Reply-To: <c22a0fd3d76675813ce5f1596d80614aee80ed24.1264568410.git.michael@ellerman.id.au>
> On 64-bit kernels we currently have a 512 byte struct paca_struct for
> each cpu (usually just called "the paca"). Currently they are statically
> allocated, which means a kernel built for a large number of cpus will
> waste a lot of space if it's booted on a machine with few cpus.
>
> We can avoid that by only allocating the number of pacas we need at
> boot. However this is complicated by the fact that we need to access
> the paca before we know how many cpus there are in the system.
>
> The solution is to dynamically allocate enough space for NR_CPUS pacas,
> but then later in boot when we know how many cpus we have, we free any
> unused pacas.
>
> Lightly booted on Legacy iSeries & pSeries LPAR.
>
> Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
<snip>
> --- a/arch/powerpc/kernel/setup-common.c
> +++ b/arch/powerpc/kernel/setup-common.c
> @@ -493,6 +493,8 @@ void __init smp_setup_cpu_maps(void)
> * here will have to be reworked
> */
> cpu_init_thread_core_maps(nthreads);
> +
> + free_unused_pacas();
This is still barfing for me on 32bit.
Putting an #include <asm/paca.h> at the top of setup-common.c fixes it.
Mikey
next prev parent reply other threads:[~2010-01-27 6:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-27 5:00 [PATCH] powerpc: Dynamically allocate pacas Michael Ellerman
2010-01-27 6:59 ` Michael Neuling [this message]
2010-01-27 22:47 ` Michael Ellerman
2010-01-27 23:27 ` Michael Neuling
2010-01-28 0:08 ` Stephen Rothwell
-- strict thread matches above, loose matches on Subject: below --
2010-01-28 23:23 Michael Ellerman
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