From 18f38f4aee3a3472f5e50786ee221d8d397bc6a8 Mon Sep 17 00:00:00 2001

Message-Id: <18f38f4aee3a3472f5e50786ee221d8d397bc6a8@dist-git>

From: Daniel Henrique Barboza <danielhb413@gmail.com>

Date: Fri, 3 May 2019 13:54:50 +0200

Subject: [PATCH] qemu: domain: Simplify non-VFIO memLockLimit calculation for

 PPC64

@passthroughLimit is being calculated even if @usesVFIO is false. After

that, an if-else conditional is used to check if we're going to sum it

up with @baseLimit.

This patch initializes @passthroughLimit to zero and always returns

@memKB = @baseLimit + @passthroughLimit. The conditional is then used to

calculate @passthroughLimit if @usesVFIO == true. This results in some

cycles being spared for the @usesVFIO == false scenario, but the real

motivation is to make the code simpler to add an alternative formula to

calculate @passthroughLimit for NVLink2.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

Reviewed-by: Erik Skultety <eskultet@redhat.com>

(cherry picked from commit cf7c5212876b2403de5b0fafedec33af4439526e)

https: //bugzilla.redhat.com/show_bug.cgi?id=1505998

Signed-off-by: Erik Skultety <eskultet@redhat.com>

Message-Id: <a6380e14dfb1c8cb463f5e3eb25bda78dc9d7dd8.1556884442.git.eskultet@redhat.com>

Reviewed-by: Andrea Bolognani <abologna@redhat.com>

---

 src/qemu/qemu_domain.c | 13 +++++--------

 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c

index cc2a896a07..d936090d87 100644

--- a/src/qemu/qemu_domain.c

+++ b/src/qemu/qemu_domain.c

@@ -9840,7 +9840,7 @@ qemuDomainGetMemLockLimitBytes(virDomainDefPtr def)

         unsigned long long maxMemory;

         unsigned long long memory;

         unsigned long long baseLimit;

-        unsigned long long passthroughLimit;

+        unsigned long long passthroughLimit = 0;

         size_t nPCIHostBridges = 0;

         bool usesVFIO = false;

@@ -9906,15 +9906,12 @@ qemuDomainGetMemLockLimitBytes(virDomainDefPtr def)

          * kiB pages, less still if the guest is mapped with hugepages (unlike

          * the default 32-bit DMA window, DDW windows can use large IOMMU

          * pages). 8 MiB is for second and further level overheads, like (b) */

-        passthroughLimit = MAX(2 * 1024 * 1024 * nPCIHostBridges,

-                               memory +

-                               memory / 512 * nPCIHostBridges + 8192);

-

         if (usesVFIO)

-            memKB = baseLimit + passthroughLimit;

-        else

-            memKB = baseLimit;

+            passthroughLimit = MAX(2 * 1024 * 1024 * nPCIHostBridges,

+                                   memory +

+                                   memory / 512 * nPCIHostBridges + 8192);

+        memKB = baseLimit + passthroughLimit;

         goto done;

     }

-- 

2.21.0