@@ -352,7 +352,7 @@ static int alloc_dispatch_log_kmem_cache(void)
}
early_initcall(alloc_dispatch_log_kmem_cache);
-static void pSeries_idle(void)
+static void pseries_lpar_idle(void)
{
/* This would call on the cpuidle framework, and the back-end pseries
* driver to go to idle states
@@ -360,10 +360,22 @@ static void pSeries_idle(void)
if (cpuidle_idle_call()) {
/* On error, execute default handler
* to go into low thread priority and possibly
- * low power mode.
+ * low power mode by cedeing processor to hypervisor
*/
- HMT_low();
- HMT_very_low();
+
+ /* Indicate to hypervisor that we are idle. */
+ get_lppaca()->idle = 1;
+
+ /*
+ * Yield the processor to the hypervisor. We return if
+ * an external interrupt occurs (which are driven prior
+ * to returning here) or if a prod occurs from another
+ * processor. When returning here, external interrupts
+ * are enabled.
+ */
+ cede_processor();
+
+ get_lppaca()->idle = 0;
}
}
@@ -395,15 +407,14 @@ static void __init pSeries_setup_arch(void)
pSeries_nvram_init();
- if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
+ if (firmware_has_feature(FW_FEATURE_LPAR)) {
vpa_init(boot_cpuid);
- ppc_md.power_save = pSeries_idle;
- }
-
- if (firmware_has_feature(FW_FEATURE_LPAR))
+ ppc_md.power_save = pseries_lpar_idle;
ppc_md.enable_pmcs = pseries_lpar_enable_pmcs;
- else
+ } else {
+ /* No special idle routine */
ppc_md.enable_pmcs = power4_enable_pmcs;
+ }
}
static int __init pSeries_init_panel(void)
This is a note to let you know that I have just added a patch titled powerpc: Default arch idle could cede processor on pseries to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.5.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 951a7b276704ab7da1fba20300eb233ab4b6c209 Mon Sep 17 00:00:00 2001 From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Date: Fri, 6 Sep 2013 00:25:06 +0530 Subject: [PATCH] powerpc: Default arch idle could cede processor on pseries commit 363edbe2614aa90df706c0f19ccfa2a6c06af0be upstream. When adding cpuidle support to pSeries, we introduced two regressions: - The new cpuidle backend driver only works under hypervisors supporting the "SLPLAR" option, which isn't the case of the old POWER4 hypervisor and the HV "light" used on js2x blades - The cpuidle driver registers fairly late, meaning that for a significant portion of the boot process, we end up having all threads spinning. This slows down the boot process and increases the overall resource usage if the hypervisor has shared processors. This fixes both by implementing a "default" idle that will cede to the hypervisor when possible, in a very simple way without all the bells and whisles of cpuidle. Reported-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> Acked-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [ luis: backported to 3.5: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/powerpc/platforms/pseries/setup.c | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) -- 1.8.3.2