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| author | Alexey Kardashevskiy | 2017-09-21 10:51:07 +0200 |
|---|---|---|
| committer | Paolo Bonzini | 2017-09-22 01:06:51 +0200 |
| commit | 092aa2fc65b7a35121616aad8f39d47b8f921618 (patch) | |
| tree | 615e8237d74d857d61c41cfa3e778a13c7892a73 /docs | |
| parent | memory: seek FlatView sharing candidates among children subregions (diff) | |
| download | qemu-092aa2fc65b7a35121616aad8f39d47b8f921618.tar.gz qemu-092aa2fc65b7a35121616aad8f39d47b8f921618.tar.xz qemu-092aa2fc65b7a35121616aad8f39d47b8f921618.zip | |
memory: Share special empty FlatView
This shares an cached empty FlatView among address spaces. The empty
FV is used every time when a root MR renders into a FV without memory
sections which happens when MR or its children are not enabled or
zero-sized. The empty_view is not NULL to keep the rest of memory
API intact; it also has a dispatch tree for the same reason.
On POWER8 with 255 CPUs, 255 virtio-net, 40 PCI bridges guest this halves
the amount of FlatView's in use (557 -> 260) and dispatch tables
(~800000 -> ~370000). In an unrelated experiment with 112 non-virtio
devices on x86 ("-M pc"), only 4 FlatViews are alive, and about ~2000
are created at startup.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-Id: <20170921085110.25598-16-aik@ozlabs.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'docs')
0 files changed, 0 insertions, 0 deletions