From: Aggelos Economopoulos <aoiko@cc.ece.ntua.gr>
Date: Sat, 5 Sep 2009 00:46:14 +0000 (+0300)
Subject: add KTR_CTXSW option to log context switches
X-Git-Url: https://gitweb.dragonflybsd.org/~polachok/dragonfly.git/commitdiff_plain/d850923cde9a684d3509eec67512169ed91f0aad

add KTR_CTXSW option to log context switches

This logs the current thread and the thread we switch
to on every context switch or thread preemption event
when enabled.
---

diff --git a/share/man/man4/ktr.4 b/share/man/man4/ktr.4
index 8bf0f6cce1..eba9f009e9 100644
--- a/share/man/man4/ktr.4
+++ b/share/man/man4/ktr.4
@@ -53,6 +53,7 @@
 .Cd options KTR_TOKENS
 .\".Cd options KTR_TSLEEP
 .Cd options KTR_USB_MEMORY
+.Cd options KTR_CTXSW
 .Sh DESCRIPTION
 The
 .Nm
@@ -119,6 +120,8 @@ IPI performance testing
 LWKT token related events
 .It Dv KTR_USB_MEMORY
 USB memory allocation
+.It Dv KTR_CTXSW
+context switches
 .El
 .Ss Verbose Mode
 By default, events are only logged to the internal buffer for examination
diff --git a/sys/conf/options b/sys/conf/options
index 1b1faf49f3..34b92c8dad 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -606,6 +606,7 @@ KTR_IFQ				opt_ktr.h
 KTR_IF_START			opt_ktr.h
 KTR_HAMMER			opt_ktr.h
 KTR_ETHERNET			opt_ktr.h
+KTR_CTXSW			opt_ktr.h
 
 # options for the Atheros driver
 ATH_DEBUG		opt_ath.h
diff --git a/sys/kern/lwkt_thread.c b/sys/kern/lwkt_thread.c
index d3359049a7..9c3be36464 100644
--- a/sys/kern/lwkt_thread.c
+++ b/sys/kern/lwkt_thread.c
@@ -68,6 +68,12 @@
 #include <machine/stdarg.h>
 #include <machine/smp.h>
 
+#if !defined(KTR_CTXSW)
+#define KTR_CTXSW KTR_ALL
+#endif
+KTR_INFO_MASTER(ctxsw);
+KTR_INFO(KTR_CTXSW, ctxsw, sw, 0, "sw  %p > %p", 2 * sizeof(struct thread *));
+KTR_INFO(KTR_CTXSW, ctxsw, pre, 1, "pre %p > %p", 2 * sizeof(struct thread *));
 
 static MALLOC_DEFINE(M_THREAD, "thread", "lwkt threads");
 
@@ -775,6 +781,7 @@ using_idle_thread:
 #ifdef __amd64__
 	KKASSERT(jg_tos_ok(ntd));
 #endif
+	KTR_LOG(ctxsw_sw, td, ntd);
 	td->td_switch(ntd);
     }
     /* NOTE: current cpu may have changed after switch */
@@ -916,6 +923,7 @@ lwkt_preempt(thread_t ntd, int critpri)
     ++preempt_hit;
     ntd->td_preempted = td;
     td->td_flags |= TDF_PREEMPT_LOCK;
+    KTR_LOG(ctxsw_pre, td, ntd);
     td->td_switch(ntd);
 
     KKASSERT(ntd->td_preempted && (td->td_flags & TDF_PREEMPT_DONE));