From: Len Brown <lenb@kernel.org>
To: x86@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Len Brown <len.brown@intel.com>
Subject: [PATCH 2/2] x86: speed cpu_up by quirking cpu_init_udelay
Date: Fri, 8 May 2015 02:37:55 -0400 [thread overview]
Message-ID: <170f6f6e9ac4aa4d8ec1ed5000bee95463897337.1431066425.git.len.brown@intel.com> (raw)
In-Reply-To: <1431067075-11449-1-git-send-email-lenb@kernel.org>
In-Reply-To: <418898b5b9a6d76e7fbbd2af7cc988de1a5a287d.1431066425.git.len.brown@intel.com>
From: Len Brown <len.brown@intel.com>
Modern processor familes are on a white-list to remove
the costly cpu_init_udelay 10000. Unknown processor families
get the traditional 10ms delay in cpu_up().
This seemed more efficient than forcing modern processors
to exhaustively search a black-list having all the old
processor families that should have a 10ms delay.
For not only are new processor familes infrequently added,
the white list also allows a delay other than 0, if needed.
Signed-off-by: Len Brown <len.brown@intel.com>
---
arch/x86/kernel/smpboot.c | 37 +++++++++++++++++++++++++++++++++++--
1 file changed, 35 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 76734f4..34a08ff 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -76,6 +76,7 @@
#include <asm/i8259.h>
#include <asm/realmode.h>
#include <asm/misc.h>
+#include <asm/cpu_device_id.h>
/* State of each CPU */
DEFINE_PER_CPU(int, cpu_state) = { 0 };
@@ -521,14 +522,44 @@ void __inquire_remote_apic(int apicid)
* that there should be a 10ms delay between the BSP asserting INIT
* and de-asserting INIT, when starting a remote processor.
* But that slows boot and resume on modern processors, which include
- * many cores and don't require that delay.
- *
+ * many cores and don't require that delay. Here we default to the
+ * legacy delay, but quirk new processors to skip the delay.
* cmdline "init_cpu_udelay=" is available to specify this delay.
*/
#define UDELAY_10MS_DEFAULT 10000
static unsigned int init_udelay = UDELAY_10MS_DEFAULT;
+static const struct x86_cpu_id init_udelay_ids[] = {
+ { X86_VENDOR_INTEL, 0x6, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0x16, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0x15, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0x14, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0x12, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0x11, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0x10, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ { X86_VENDOR_AMD, 0xF, X86_MODEL_ANY, X86_FEATURE_ANY, 0 },
+ {}
+};
+MODULE_DEVICE_TABLE(x86cpu, init_udelay_ids);
+
+static void __init smp_quirk_init_udelay(void)
+{
+ const struct x86_cpu_id *id;
+ unsigned int new_udelay;
+
+ id = x86_match_cpu(init_udelay_ids);
+ if (id == NULL)
+ return; /* if no match, keep default */
+
+ if (init_udelay != UDELAY_10MS_DEFAULT)
+ return; /* if cmdline changed from default, leave it alone */
+
+ new_udelay = (unsigned long) id->driver_data;
+ pr_debug("cpu_init_udelay quirk to %d, was %d", new_udelay, init_udelay);
+ init_udelay = new_udelay;
+}
+
static int __init cpu_init_udelay(char *str)
{
unsigned int new_udelay;
@@ -1196,6 +1227,8 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
uv_system_init();
set_mtrr_aps_delayed_init();
+
+ smp_quirk_init_udelay();
}
void arch_enable_nonboot_cpus_begin(void)
--
2.4.0.rc1
next prev parent reply other threads:[~2015-05-08 6:38 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-08 6:37 [PATCH 0/2 v2] speeding up cpu_up() Len Brown
2015-05-08 6:37 ` [PATCH 1/2] x86: replace cpu_up hard-coded mdelay with variable udelay Len Brown
2015-05-08 6:37 ` Len Brown [this message]
2015-05-08 7:51 ` [PATCH 2/2] x86: speed cpu_up by quirking cpu_init_udelay Ingo Molnar
2015-05-08 8:23 ` Borislav Petkov
2015-05-08 8:32 ` Borislav Petkov
2015-05-08 18:15 ` Len Brown
2015-05-08 18:27 ` Borislav Petkov
2015-05-09 7:22 ` Ingo Molnar
2015-05-09 7:24 ` Ingo Molnar
2015-05-09 8:04 ` Borislav Petkov
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