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https://github.com/torvalds/linux
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d063de55f4
If guest kernel is configured with nopvspin, or CONFIG_PARAVIRT_SPINLOCK
is disabled, or guest find its has dedicated pCPUs from realtime hint
feature, the pvspinlock will be disabled, and vCPU preemption check
is disabled too.
Hoever, KVM still can emulating HLT for vCPU for both cases. Checking if a vCPU
is preempted or not can still boost performance in IPI-heavy scenarios such as
unixbench file copy and pipe-based context switching tests: Here the vCPU is
running with a dedicated pCPU, so the guest kernel has nopvspin but is
emulating HLT for the vCPU:
Testcase Base with patch
System Benchmarks Index Values INDEX INDEX
Dhrystone 2 using register variables 3278.4 3277.7
Double-Precision Whetstone 822.8 825.8
Execl Throughput 1296.5 941.1
File Copy 1024 bufsize 2000 maxblocks 2124.2 2142.7
File Copy 256 bufsize 500 maxblocks 1335.9 1353.6
File Copy 4096 bufsize 8000 maxblocks 4256.3 4760.3
Pipe Throughput 1050.1 1054.0
Pipe-based Context Switching 243.3 352.0
Process Creation 820.1 814.4
Shell Scripts (1 concurrent) 2169.0 2086.0
Shell Scripts (8 concurrent) 7710.3 7576.3
System Call Overhead 672.4 673.9
======== =======
System Benchmarks Index Score 1467.2 1483.0
Move the setting of pv_ops.lock.vcpu_is_preempted to kvm_guest_init, so
that it does not depend on pvspinlock.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Message-Id: <1646815610-43315-1-git-send-email-lirongqing@baidu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
65 lines
1.1 KiB
C
65 lines
1.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifndef __LINUX_KBUILD_H
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# error "Please do not build this file directly, build asm-offsets.c instead"
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#endif
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#include <asm/ia32.h>
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#if defined(CONFIG_KVM_GUEST)
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#include <asm/kvm_para.h>
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#endif
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int main(void)
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{
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#ifdef CONFIG_PARAVIRT
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#ifdef CONFIG_PARAVIRT_XXL
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#ifdef CONFIG_DEBUG_ENTRY
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OFFSET(PV_IRQ_save_fl, paravirt_patch_template, irq.save_fl);
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#endif
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#endif
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BLANK();
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#endif
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#if defined(CONFIG_KVM_GUEST)
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OFFSET(KVM_STEAL_TIME_preempted, kvm_steal_time, preempted);
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BLANK();
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#endif
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#define ENTRY(entry) OFFSET(pt_regs_ ## entry, pt_regs, entry)
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ENTRY(bx);
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ENTRY(cx);
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ENTRY(dx);
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ENTRY(sp);
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ENTRY(bp);
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ENTRY(si);
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ENTRY(di);
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ENTRY(r8);
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ENTRY(r9);
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ENTRY(r10);
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ENTRY(r11);
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ENTRY(r12);
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ENTRY(r13);
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ENTRY(r14);
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ENTRY(r15);
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ENTRY(flags);
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BLANK();
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#undef ENTRY
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#define ENTRY(entry) OFFSET(saved_context_ ## entry, saved_context, entry)
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ENTRY(cr0);
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ENTRY(cr2);
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ENTRY(cr3);
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ENTRY(cr4);
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ENTRY(gdt_desc);
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BLANK();
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#undef ENTRY
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BLANK();
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#ifdef CONFIG_STACKPROTECTOR
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DEFINE(stack_canary_offset, offsetof(struct fixed_percpu_data, stack_canary));
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BLANK();
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#endif
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return 0;
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}
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