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From: Yanan Wang <wangyanan55@huawei.com>
To: <qemu-devel@nongnu.org>
Cc: "Peter Maydell" <peter.maydell@linaro.org>,
	"Andrew Jones" <drjones@redhat.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Daniel P . Berrangé" <berrange@redhat.com>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Pierre Morel" <pmorel@linux.ibm.com>,
	"Michael S . Tsirkin" <mst@redhat.com>,
	"Pankaj Gupta" <pankaj.gupta.linux@gmail.com>,
	"Richard Henderson" <richard.henderson@linaro.org>,
	"Greg Kurz" <groug@kaod.org>, "Halil Pasic" <pasic@linux.ibm.com>,
	wanghaibin.wang@huawei.com, "Thomas Huth" <thuth@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Yanan Wang" <wangyanan55@huawei.com>,
	"David Gibson" <david@gibson.dropbear.id.au>
Subject: [PATCH v7 03/15] machine: Uniformly use maxcpus to calculate the omitted parameters
Date: Mon, 23 Aug 2021 20:27:52 +0800	[thread overview]
Message-ID: <20210823122804.7692-4-wangyanan55@huawei.com> (raw)
In-Reply-To: <20210823122804.7692-1-wangyanan55@huawei.com>

We are currently using maxcpus to calculate the omitted sockets
but using cpus to calculate the omitted cores/threads. This makes
cmdlines like:
  -smp cpus=8,maxcpus=16
  -smp cpus=8,cores=4,maxcpus=16
  -smp cpus=8,threads=2,maxcpus=16
work fine but the ones like:
  -smp cpus=8,sockets=2,maxcpus=16
  -smp cpus=8,sockets=2,cores=4,maxcpus=16
  -smp cpus=8,sockets=2,threads=2,maxcpus=16
break the sanity check.

Since we require for a valid config that the product of "sockets * cores
* threads" should equal to the maxcpus, we should uniformly use maxcpus
to calculate their omitted values.

Also the if-branch of "cpus == 0 || sockets == 0" was split into two
branches of "cpus == 0" and "sockets == 0" so that we can clearly read
that we are parsing the configuration with a preference on cpus over
sockets over cores over threads.

Note: change in this patch won't affect any existing working cmdlines
but improves consistency and allows more incomplete configs to be valid.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@ionos.com>
---
 hw/core/machine.c | 30 +++++++++++++++---------------
 hw/i386/pc.c      | 30 +++++++++++++++---------------
 2 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index bcced1e1c4..dc12b5ec4e 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -757,24 +757,26 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
     }
 
     /* compute missing values, prefer sockets over cores over threads */
-    if (cpus == 0 || sockets == 0) {
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
+
+    if (cpus == 0) {
+        sockets = sockets > 0 ? sockets : 1;
         cores = cores > 0 ? cores : 1;
         threads = threads > 0 ? threads : 1;
-        if (cpus == 0) {
-            sockets = sockets > 0 ? sockets : 1;
-            cpus = cores * threads * sockets;
-        } else {
-            maxcpus = maxcpus > 0 ? maxcpus : cpus;
-            sockets = maxcpus / (cores * threads);
-        }
+        cpus = sockets * cores * threads;
+        maxcpus = maxcpus > 0 ? maxcpus : cpus;
+    } else if (sockets == 0) {
+        cores = cores > 0 ? cores : 1;
+        threads = threads > 0 ? threads : 1;
+        sockets = maxcpus / (cores * threads);
     } else if (cores == 0) {
         threads = threads > 0 ? threads : 1;
-        cores = cpus / (sockets * threads);
-        cores = cores > 0 ? cores : 1;
+        cores = maxcpus / (sockets * threads);
     } else if (threads == 0) {
-        threads = cpus / (cores * sockets);
-        threads = threads > 0 ? threads : 1;
-    } else if (sockets * cores * threads < cpus) {
+        threads = maxcpus / (sockets * cores);
+    }
+
+    if (sockets * cores * threads < cpus) {
         error_setg(errp, "cpu topology: "
                    "sockets (%u) * cores (%u) * threads (%u) < "
                    "smp_cpus (%u)",
@@ -782,8 +784,6 @@ static void smp_parse(MachineState *ms, SMPConfiguration *config, Error **errp)
         return;
     }
 
-    maxcpus = maxcpus > 0 ? maxcpus : cpus;
-
     if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index acd31af452..a9ff9ef52c 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -725,24 +725,26 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
     dies = dies > 0 ? dies : 1;
 
     /* compute missing values, prefer sockets over cores over threads */
-    if (cpus == 0 || sockets == 0) {
+    maxcpus = maxcpus > 0 ? maxcpus : cpus;
+
+    if (cpus == 0) {
+        sockets = sockets > 0 ? sockets : 1;
         cores = cores > 0 ? cores : 1;
         threads = threads > 0 ? threads : 1;
-        if (cpus == 0) {
-            sockets = sockets > 0 ? sockets : 1;
-            cpus = cores * threads * dies * sockets;
-        } else {
-            maxcpus = maxcpus > 0 ? maxcpus : cpus;
-            sockets = maxcpus / (dies * cores * threads);
-        }
+        cpus = sockets * dies * cores * threads;
+        maxcpus = maxcpus > 0 ? maxcpus : cpus;
+    } else if (sockets == 0) {
+        cores = cores > 0 ? cores : 1;
+        threads = threads > 0 ? threads : 1;
+        sockets = maxcpus / (dies * cores * threads);
     } else if (cores == 0) {
         threads = threads > 0 ? threads : 1;
-        cores = cpus / (sockets * dies * threads);
-        cores = cores > 0 ? cores : 1;
+        cores = maxcpus / (sockets * dies * threads);
     } else if (threads == 0) {
-        threads = cpus / (cores * dies * sockets);
-        threads = threads > 0 ? threads : 1;
-    } else if (sockets * dies * cores * threads < cpus) {
+        threads = maxcpus / (sockets * dies * cores);
+    }
+
+    if (sockets * dies * cores * threads < cpus) {
         error_setg(errp, "cpu topology: "
                    "sockets (%u) * dies (%u) * cores (%u) * threads (%u) < "
                    "smp_cpus (%u)",
@@ -750,8 +752,6 @@ static void pc_smp_parse(MachineState *ms, SMPConfiguration *config, Error **err
         return;
     }
 
-    maxcpus = maxcpus > 0 ? maxcpus : cpus;
-
     if (maxcpus < cpus) {
         error_setg(errp, "maxcpus must be equal to or greater than smp");
         return;
-- 
2.19.1



  parent reply	other threads:[~2021-08-23 12:34 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 12:27 [PATCH v7 00/15] machine: smp parsing fixes and improvement Yanan Wang
2021-08-23 12:27 ` [PATCH v7 01/15] machine: Deprecate "parameter=0" SMP configurations Yanan Wang
2021-08-23 12:27 ` [PATCH v7 02/15] machine: Minor refactor/fix for the smp parsers Yanan Wang
2021-08-23 12:27 ` Yanan Wang [this message]
2021-08-23 12:27 ` [PATCH v7 04/15] machine: Set the value of cpus to match maxcpus if it's omitted Yanan Wang
2021-08-23 12:27 ` [PATCH v7 05/15] machine: Improve the error reporting of smp parsing Yanan Wang
2021-08-23 13:17   ` Philippe Mathieu-Daudé
2021-08-24  4:51     ` wangyanan (Y)
2021-08-24  7:29       ` Philippe Mathieu-Daudé
2021-08-24  8:23         ` wangyanan (Y)
2021-08-23 12:27 ` [PATCH v7 06/15] hw: Add compat machines for 6.2 Yanan Wang
2021-08-23 12:27 ` [PATCH v7 07/15] machine: Prefer cores over sockets in smp parsing since 6.2 Yanan Wang
2021-08-23 12:27 ` [PATCH v7 08/15] machine: Use ms instead of global current_machine in sanity-check Yanan Wang
2021-08-23 12:27 ` [PATCH v7 09/15] machine: Tweak the order of topology members in struct CpuTopology Yanan Wang
2021-08-23 12:27 ` [PATCH v7 10/15] machine: Make smp_parse generic enough for all arches Yanan Wang
2021-08-23 13:19   ` Philippe Mathieu-Daudé
2021-08-23 12:28 ` [PATCH v7 11/15] machine: Remove smp_parse callback from MachineClass Yanan Wang
2021-08-23 12:28 ` [PATCH v7 12/15] machine: Move smp_prefer_sockets to struct SMPCompatProps Yanan Wang
2021-08-23 12:28 ` [PATCH v7 13/15] machine: Put all sanity-check in the generic SMP parser Yanan Wang
2021-08-23 12:28 ` [PATCH v7 14/15] machine: Split out the smp parsing code Yanan Wang
2021-08-23 12:28 ` [PATCH v7 15/15] tests/unit: Add a unit test for smp parsing Yanan Wang

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