diff options
| author | Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> | 2023-09-05 10:12:46 +0100 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2023-09-08 16:41:36 +0100 |
| commit | c8f2eb5d414b788420b938f2ffdde891aa6c3ae8 (patch) | |
| tree | 31e339b0f3f4c21d6961ade03485aa1ad9ad1d1e /qemu-options.hx | |
| parent | d03396a8bb19b77d4d0fa2ad2143999510f0d44e (diff) | |
arm/kvm: Enable support for KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE
Now that we have Eager Page Split support added for ARM in the kernel,
enable it in Qemu. This adds,
-eager-split-size to -accel sub-options to set the eager page split chunk size.
-enable KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE.
The chunk size specifies how many pages to break at a time, using a
single allocation. Bigger the chunk size, more pages need to be
allocated ahead of time.
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Message-id: 20230905091246.1931-1-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'qemu-options.hx')
| -rw-r--r-- | qemu-options.hx | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/qemu-options.hx b/qemu-options.hx index 463f520c57..93d106aa9c 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -186,6 +186,7 @@ DEF("accel", HAS_ARG, QEMU_OPTION_accel, " split-wx=on|off (enable TCG split w^x mapping)\n" " tb-size=n (TCG translation block cache size)\n" " dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n" + " eager-split-size=n (KVM Eager Page Split chunk size, default 0, disabled. ARM only)\n" " notify-vmexit=run|internal-error|disable,notify-window=n (enable notify VM exit and set notify window, x86 only)\n" " thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL) SRST @@ -244,6 +245,20 @@ SRST is disabled (dirty-ring-size=0). When enabled, KVM will instead record dirty pages in a bitmap. + ``eager-split-size=n`` + KVM implements dirty page logging at the PAGE_SIZE granularity and + enabling dirty-logging on a huge-page requires breaking it into + PAGE_SIZE pages in the first place. KVM on ARM does this splitting + lazily by default. There are performance benefits in doing huge-page + split eagerly, especially in situations where TLBI costs associated + with break-before-make sequences are considerable and also if guest + workloads are read intensive. The size here specifies how many pages + to break at a time and needs to be a valid block size which is + 1GB/2MB/4KB, 32MB/16KB and 512MB/64KB for 4KB/16KB/64KB PAGE_SIZE + respectively. Be wary of specifying a higher size as it will have an + impact on the memory. By default, this feature is disabled + (eager-split-size=0). + ``notify-vmexit=run|internal-error|disable,notify-window=n`` Enables or disables notify VM exit support on x86 host and specify the corresponding notify window to trigger the VM exit if enabled. |