On 16.05.24 15:02, Chen Yu wrote:
Performance drop is reported when running encode/decode workload and
BenchSEE cache sub-workload.
Bisect points to commit ce0a1b608bfc ("x86/paravirt: Silence unused
native_pv_lock_init() function warning"). When CONFIG_PARAVIRT_SPINLOCKS
is disabled the virt_spin_lock_key is set to true on bare-metal.
The qspinlock degenerates to test-and-set spinlock, which decrease the
performance on bare-metal.
Fix this by disabling virt_spin_lock_key if CONFIG_PARAVIRT_SPINLOCKS
is not set, or it is on bare-metal.
Fixes: ce0a1b608bfc ("x86/paravirt: Silence unused native_pv_lock_init() function warning")
Suggested-by: Qiuxu Zhuo <qiuxu.zhuo@xxxxxxxxx>
Reported-by: Prem Nath Dey <prem.nath.dey@xxxxxxxxx>
Reported-by: Xiaoping Zhou <xiaoping.zhou@xxxxxxxxx>
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
Reviewed-by: Juergen Gross <jgross@xxxxxxxx> Juergen
--- arch/x86/kernel/paravirt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 5358d43886ad..ee51c0949ed8 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -55,7 +55,7 @@ DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);void __init native_pv_lock_init(void){ - if (IS_ENABLED(CONFIG_PARAVIRT_SPINLOCKS) && + if (!IS_ENABLED(CONFIG_PARAVIRT_SPINLOCKS) || !boot_cpu_has(X86_FEATURE_HYPERVISOR)) static_branch_disable(&virt_spin_lock_key); }
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