46 lines
1.9 KiB
Diff
46 lines
1.9 KiB
Diff
From 1a1ea4307536f142aff5ea17b9dc73ffe3a35c79 Mon Sep 17 00:00:00 2001
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From: Jaroslav Jindrak <dzejrou@gmail.com>
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Date: Tue, 17 May 2022 14:38:58 +0200
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Subject: [PATCH 3/3] hostmem: default the amount of prealloc-threads to
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smp-cpus
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Prior to the introduction of the prealloc-threads property, the amount
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of threads used to preallocate memory was derived from the value of
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smp-cpus passed to qemu, the amount of physical cpus of the host
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and a hardcoded maximum value. When the prealloc-threads property
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was introduced, it included a default of 1 in backends/hostmem.c and
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a default of smp-cpus using the sugar API for the property itself. The
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latter default is not used when the property is not specified on qemu's
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command line, so guests that were not adjusted for this change suddenly
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started to use the default of 1 thread to preallocate memory, which
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resulted in observable slowdowns in guest boots for guests with large
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memory (e.g. when using libvirt <8.2.0 or managing guests manually).
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This commit restores the original behavior for these cases while not
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impacting guests started with the prealloc-threads property in any way.
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Fixes: 220c1fd864e9d ("hostmem: introduce "prealloc-threads" property")
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Signed-off-by: Jaroslav Jindrak <dzejrou@gmail.com>
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Message-Id: <20220517123858.7933-1-dzejrou@gmail.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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---
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backends/hostmem.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/backends/hostmem.c b/backends/hostmem.c
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index 4c05862ed5..c9ddaec849 100644
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--- a/backends/hostmem.c
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+++ b/backends/hostmem.c
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@@ -273,7 +273,7 @@ static void host_memory_backend_init(Object *obj)
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backend->merge = machine_mem_merge(machine);
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backend->dump = machine_dump_guest_core(machine);
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backend->reserve = true;
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- backend->prealloc_threads = 1;
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+ backend->prealloc_threads = machine->smp.cpus;
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}
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static void host_memory_backend_post_init(Object *obj)
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--
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2.27.0
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