RFC: [PATCH v1] KVM: Use trace_printk() for vcpu_unimpl() for performance reasons
vcpu_unimpl() is called to notify for example about unhandled wrmsr requests made by KVM guests. It used to call printk() but in certain setups printk() may cause severe performance impact thus replacing printk() with guaranteed to be buffered trace_printk() avoids this caveat.
Signed-off-by Ilari Stenroth <[email protected]>
--- include/linux/kvm_host.h | 8 ++++++++ 1 file changed, 8 insertions(+)
include/linux/kvm_host.h +8 -0
@@ -24,6 +24,8 @@#include <linux/err.h> #include <linux/irqflags.h> #include <linux/context_tracking.h> +#include <linux/kernel.h> +#include <linux/kern_levels.h> #include <asm/signal.h> #include <linux/kvm.h>
@@ -408,9 +410,15 @@ struct kvm { pr_info("kvm [%i]: " fmt, task_pid_nr(current), ## __VA_ARGS__)#define kvm_debug (fmt, ...) \ pr_debug("kvm [%i]: " fmt, task_pid_nr(current), ## __VA_ARGS__) +#ifdef CONFIG_TRACING +#define kvm_pr_unimpl (fmt, ...) \ + trace_printk(pr_fmt("KERN_ERR kvm [%i]: " fmt), \ + task_tgid_nr(current), ## __VA_ARGS__) +#else #define kvm_pr_unimpl (fmt, ...) \ pr_err_ratelimited("kvm [%i]: " fmt, \ task_tgid_nr(current), ## __VA_ARGS__) +#endif /* The guest did something we don't support. */ #define vcpu_unimpl (vcpu, fmt, ...) \
Signature · 1 line
2.0.4