swh:1:snp:32555a3fd8878f019c2ebd6c964bc1edcaeff337
Revision 0c5f81dad46c90792e6c3c4797131323c9e96dcd authored by Wanpeng Li on 06 July 2019, 01:26:51 UTC, committed by Paolo Bonzini on 20 July 2019, 07:00:40 UTC
Dedicated instances are currently disturbed by unnecessary jitter due to the emulated lapic timers firing on the same pCPUs where the vCPUs reside. There is no hardware virtual timer on Intel for guest like ARM, so both programming timer in guest and the emulated timer fires incur vmexits. This patch tries to avoid vmexit when the emulated timer fires, at least in dedicated instance scenario when nohz_full is enabled. In that case, the emulated timers can be offload to the nearest busy housekeeping cpus since APICv has been found for several years in server processors. The guest timer interrupt can then be injected via posted interrupts, which are delivered by the housekeeping cpu once the emulated timer fires. The host should tuned so that vCPUs are placed on isolated physical processors, and with several pCPUs surplus for busy housekeeping. If disabled mwait/hlt/pause vmexits keep the vCPUs in non-root mode, ~3% redis performance benefit can be observed on Skylake server, and the number of external interrupt vmexits drops substantially. Without patch VM-EXIT Samples Samples% Time% Min Time Max Time Avg time EXTERNAL_INTERRUPT 42916 49.43% 39.30% 0.47us 106.09us 0.71us ( +- 1.09% ) While with patch: VM-EXIT Samples Samples% Time% Min Time Max Time Avg time EXTERNAL_INTERRUPT 6871 9.29% 2.96% 0.44us 57.88us 0.72us ( +- 4.02% ) Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
1 parent 4d151bf
Tip revision: ffb4d94b4314655cea60ab7962756e6bab72fc7e authored by Linus Torvalds on 30 September 2022, 23:25:52 UTC
Merge tag 'drm-fixes-2022-10-01' of git://anongit.freedesktop.org/drm/drm
Merge tag 'drm-fixes-2022-10-01' of git://anongit.freedesktop.org/drm/drm
Tip revision: ffb4d94
File | Mode | Size |
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Documentation | ||
LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 14.6 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 71 bytes |
.gitattributes | -rw-r--r-- | 30 bytes |
.gitignore | -rw-r--r-- | 1.6 KB |
.mailmap | -rw-r--r-- | 12.0 KB |
COPYING | -rw-r--r-- | 423 bytes |
CREDITS | -rw-r--r-- | 97.2 KB |
Kbuild | -rw-r--r-- | 1.5 KB |
Kconfig | -rw-r--r-- | 595 bytes |
MAINTAINERS | -rw-r--r-- | 506.0 KB |
Makefile | -rw-r--r-- | 59.3 KB |
README | -rw-r--r-- | 727 bytes |
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