From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: Nathan Lynch <ntl@pobox•com>
Cc: linuxppc-dev@ozlabs•org
Subject: Re: [PATCH] kill useless SMT code in prom_hold_cpus
Date: Tue, 15 Jul 2008 12:05:55 +1000 [thread overview]
Message-ID: <1216087555.7740.42.camel@pasglop> (raw)
In-Reply-To: <20080708223631.GP9594@localdomain>
On Tue, 2008-07-08 at 17:36 -0500, Nathan Lynch wrote:
> I think this code that counts SMT threads and compares against NR_CPUS
> is an artifact of pre-powerpc-merge ppc64. We care about starting
> only primary threads in the OF client code.
>
> Signed-off-by: Nathan Lynch <ntl@pobox•com>
That looks good. I'm not merging it right now because I want to dbl
check that it's allright on all SMT machines. IE. We compare reg[0]
against _prom->cpu now instead of interrupt_server[0] and I thus
want to ensure it's the same everywhere.
Cheers,
Ben.
> arch/powerpc/kernel/prom_init.c | 39 +++------------------------------------
> 1 files changed, 3 insertions(+), 36 deletions(-)
>
> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
> index 1ea8c8d..b1dd86c 100644
> --- a/arch/powerpc/kernel/prom_init.c
> +++ b/arch/powerpc/kernel/prom_init.c
> @@ -205,8 +205,6 @@ static int __initdata mem_reserve_cnt;
> static cell_t __initdata regbuf[1024];
>
>
> -#define MAX_CPU_THREADS 2
> -
> /*
> * Error results ... some OF calls will return "-1" on error, some
> * will return 0, some will return either. To simplify, here are
> @@ -1332,10 +1330,6 @@ static void __init prom_hold_cpus(void)
> unsigned int reg;
> phandle node;
> char type[64];
> - int cpuid = 0;
> - unsigned int interrupt_server[MAX_CPU_THREADS];
> - unsigned int cpu_threads, hw_cpu_num;
> - int propsize;
> struct prom_t *_prom = &RELOC(prom);
> unsigned long *spinloop
> = (void *) LOW_ADDR(__secondary_hold_spinloop);
> @@ -1379,7 +1373,6 @@ static void __init prom_hold_cpus(void)
> reg = -1;
> prom_getprop(node, "reg", ®, sizeof(reg));
>
> - prom_debug("\ncpuid = 0x%x\n", cpuid);
> prom_debug("cpu hw idx = 0x%x\n", reg);
>
> /* Init the acknowledge var which will be reset by
> @@ -1388,28 +1381,9 @@ static void __init prom_hold_cpus(void)
> */
> *acknowledge = (unsigned long)-1;
>
> - propsize = prom_getprop(node, "ibm,ppc-interrupt-server#s",
> - &interrupt_server,
> - sizeof(interrupt_server));
> - if (propsize < 0) {
> - /* no property. old hardware has no SMT */
> - cpu_threads = 1;
> - interrupt_server[0] = reg; /* fake it with phys id */
> - } else {
> - /* We have a threaded processor */
> - cpu_threads = propsize / sizeof(u32);
> - if (cpu_threads > MAX_CPU_THREADS) {
> - prom_printf("SMT: too many threads!\n"
> - "SMT: found %x, max is %x\n",
> - cpu_threads, MAX_CPU_THREADS);
> - cpu_threads = 1; /* ToDo: panic? */
> - }
> - }
> -
> - hw_cpu_num = interrupt_server[0];
> - if (hw_cpu_num != _prom->cpu) {
> + if (reg != _prom->cpu) {
> /* Primary Thread of non-boot cpu */
> - prom_printf("%x : starting cpu hw idx %x... ", cpuid, reg);
> + prom_printf("starting cpu hw idx %x... ", reg);
> call_prom("start-cpu", 3, 0, node,
> secondary_hold, reg);
>
> @@ -1424,17 +1398,10 @@ static void __init prom_hold_cpus(void)
> }
> #ifdef CONFIG_SMP
> else
> - prom_printf("%x : boot cpu %x\n", cpuid, reg);
> + prom_printf("boot cpu hw idx %x\n", reg);
> #endif /* CONFIG_SMP */
> -
> - /* Reserve cpu #s for secondary threads. They start later. */
> - cpuid += cpu_threads;
> }
>
> - if (cpuid > NR_CPUS)
> - prom_printf("WARNING: maximum CPUs (" __stringify(NR_CPUS)
> - ") exceeded: ignoring extras\n");
> -
> prom_debug("prom_hold_cpus: end...\n");
> }
>
next prev parent reply other threads:[~2008-07-15 2:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-08 22:36 [PATCH] kill useless SMT code in prom_hold_cpus Nathan Lynch
2008-07-15 2:05 ` Benjamin Herrenschmidt [this message]
2008-07-15 2:24 ` Nathan Lynch
2008-07-15 4:53 ` Benjamin Herrenschmidt
2008-07-15 2:22 ` Tony Breeds
2008-07-15 4:55 ` Nathan Lynch
2008-07-15 4:59 ` Tony Breeds
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