linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Anton Blanchard <anton@ozlabs.org>,
	"Oliver O'Halloran" <oohall@gmail.com>,
	Nathan Lynch <nathanl@linux.ibm.com>,
	Michael Neuling <mikey@neuling.org>,
	Gautham R Shenoy <ego@linux.vnet.ibm.com>,
	Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
	Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Valentin Schneider <valentin.schneider@arm.com>
Subject: [PATCH v2 02/11] powerpc/smp: Stop updating cpu_core_mask
Date: Mon, 21 Sep 2020 15:26:44 +0530	[thread overview]
Message-ID: <20200921095653.9701-3-srikar@linux.vnet.ibm.com> (raw)
In-Reply-To: <20200921095653.9701-1-srikar@linux.vnet.ibm.com>

Anton Blanchard reported that his 4096 vcpu KVM guest took around 30
minutes to boot. He also analyzed it to the time taken to iterate while
setting the cpu_core_mask.

Further analysis shows that cpu_core_mask and cpu_cpu_mask for any CPU
would be equal on Power. However updating cpu_core_mask took forever to
update as its a per cpu cpumask variable. Instead cpu_cpu_mask was a per
NODE /per DIE cpumask that was shared by all the respective CPUs.

Also cpu_cpu_mask is needed from a scheduler perspective. However
cpu_core_map is an exported symbol. Hence stop updating cpu_core_map
and make it point to cpu_cpu_mask.

Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Oliver O'Halloran <oohall@gmail.com>
Cc: Nathan Lynch <nathanl@linux.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
Cc: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Tested-by: Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/smp.h |  5 -----
 arch/powerpc/kernel/smp.c      | 33 +++++++--------------------------
 2 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/arch/powerpc/include/asm/smp.h b/arch/powerpc/include/asm/smp.h
index 041f0b97c45b..40e121dd16af 100644
--- a/arch/powerpc/include/asm/smp.h
+++ b/arch/powerpc/include/asm/smp.h
@@ -119,11 +119,6 @@ static inline struct cpumask *cpu_sibling_mask(int cpu)
 	return per_cpu(cpu_sibling_map, cpu);
 }
 
-static inline struct cpumask *cpu_core_mask(int cpu)
-{
-	return per_cpu(cpu_core_map, cpu);
-}
-
 static inline struct cpumask *cpu_l2_cache_mask(int cpu)
 {
 	return per_cpu(cpu_l2_cache_map, cpu);
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 3d96752d6570..ec41491beca4 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -953,12 +953,17 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 				local_memory_node(numa_cpu_lookup_table[cpu]));
 		}
 #endif
+		/*
+		 * cpu_core_map is now more updated and exists only since
+		 * its been exported for long. It only will have a snapshot
+		 * of cpu_cpu_mask.
+		 */
+		cpumask_copy(per_cpu(cpu_core_map, cpu), cpu_cpu_mask(cpu));
 	}
 
 	/* Init the cpumasks so the boot CPU is related to itself */
 	cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
 	cpumask_set_cpu(boot_cpuid, cpu_l2_cache_mask(boot_cpuid));
-	cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
 
 	if (has_coregroup_support())
 		cpumask_set_cpu(boot_cpuid, cpu_coregroup_mask(boot_cpuid));
@@ -1260,9 +1265,7 @@ static void remove_cpu_from_masks(int cpu)
 {
 	int i;
 
-	/* NB: cpu_core_mask is a superset of the others */
-	for_each_cpu(i, cpu_core_mask(cpu)) {
-		set_cpus_unrelated(cpu, i, cpu_core_mask);
+	for_each_cpu(i, cpu_cpu_mask(cpu)) {
 		set_cpus_unrelated(cpu, i, cpu_l2_cache_mask);
 		set_cpus_unrelated(cpu, i, cpu_sibling_mask);
 		if (has_big_cores)
@@ -1312,7 +1315,6 @@ EXPORT_SYMBOL_GPL(get_physical_package_id);
 static void add_cpu_to_masks(int cpu)
 {
 	int first_thread = cpu_first_thread_sibling(cpu);
-	int pkg_id = get_physical_package_id(cpu);
 	int i;
 
 	/*
@@ -1320,7 +1322,6 @@ static void add_cpu_to_masks(int cpu)
 	 * add it to it's own thread sibling mask.
 	 */
 	cpumask_set_cpu(cpu, cpu_sibling_mask(cpu));
-	cpumask_set_cpu(cpu, cpu_core_mask(cpu));
 
 	for (i = first_thread; i < first_thread + threads_per_core; i++)
 		if (cpu_online(i))
@@ -1342,26 +1343,6 @@ static void add_cpu_to_masks(int cpu)
 				set_cpus_related(cpu, i, cpu_coregroup_mask);
 		}
 	}
-
-	if (pkg_id == -1) {
-		struct cpumask *(*mask)(int) = cpu_sibling_mask;
-
-		/*
-		 * Copy the sibling mask into core sibling mask and
-		 * mark any CPUs on the same chip as this CPU.
-		 */
-		if (shared_caches)
-			mask = cpu_l2_cache_mask;
-
-		for_each_cpu(i, mask(cpu))
-			set_cpus_related(cpu, i, cpu_core_mask);
-
-		return;
-	}
-
-	for_each_cpu(i, cpu_online_mask)
-		if (get_physical_package_id(i) == pkg_id)
-			set_cpus_related(cpu, i, cpu_core_mask);
 }
 
 /* Activate a secondary processor. */
-- 
2.17.1


  parent reply	other threads:[~2020-09-21  9:57 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21  9:56 [PATCH v2 00/11] Optimization to improve CPU online/offline on Powerpc Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 01/11] powerpc/topology: Update topology_core_cpumask Srikar Dronamraju
2020-09-21  9:56 ` Srikar Dronamraju [this message]
2020-09-21  9:56 ` [PATCH v2 03/11] powerpc/smp: Remove get_physical_package_id Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 04/11] powerpc/smp: Optimize remove_cpu_from_masks Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 05/11] powerpc/smp: Limit CPUs traversed to within a node Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 06/11] powerpc/smp: Stop passing mask to update_mask_by_l2 Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 07/11] powerpc/smp: Depend on cpu_l1_cache_map when adding CPUs Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 08/11] powerpc/smp: Check for duplicate topologies and consolidate Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 09/11] powerpc/smp: Optimize update_mask_by_l2 Srikar Dronamraju
2020-10-07 13:05   ` Qian Cai
2020-10-07 14:17     ` Srikar Dronamraju
2020-10-07 14:23       ` Qian Cai
2020-09-21  9:56 ` [PATCH v2 10/11] powerpc/smp: Move coregroup mask updation to a new function Srikar Dronamraju
2020-09-21  9:56 ` [PATCH v2 11/11] powerpc/smp: Optimize update_coregroup_mask Srikar Dronamraju
2020-10-07  3:21 ` [PATCH v2 00/11] Optimization to improve CPU online/offline on Powerpc Michael Ellerman

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200921095653.9701-3-srikar@linux.vnet.ibm.com \
    --to=srikar@linux.vnet.ibm.com \
    --cc=anton@ozlabs.org \
    --cc=ego@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mikey@neuling.org \
    --cc=mingo@kernel.org \
    --cc=mpe@ellerman.id.au \
    --cc=nathanl@linux.ibm.com \
    --cc=npiggin@gmail.com \
    --cc=oohall@gmail.com \
    --cc=peterz@infradead.org \
    --cc=sathnaga@linux.vnet.ibm.com \
    --cc=valentin.schneider@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).