Date: Fri, 23 Dec 2011 15:20:00 -0500 From: John Baldwin <jhb@freebsd.org> To: arch@freebsd.org Subject: Teach KTR_SCHED to handle changing thread names Message-ID: <201112231520.00282.jhb@freebsd.org>
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When I use the new schedgraph on 8, I find that it commonly calls almost all
threads "sh" or "tcsh" because it only uses the name from the initial fork and
never notices when a thread changes its name via exec. This makes traces
harder to follow. The patch below adds a hook to clear the cached thread name
to force it to be regenerated on the next trace when td_name changes. This
makes the traces more usable for me at least.
Index: kern/sched_ule.c
===================================================================
--- kern/sched_ule.c (revision 225431)
+++ kern/sched_ule.c (working copy)
@@ -2685,6 +2685,17 @@
#endif
}
+#ifdef KTR
+void
+sched_clear_tdname(struct thread *td)
+{
+ struct td_sched *ts;
+
+ ts = td->td_sched;
+ ts->ts_name[0] = '\0';
+}
+#endif
+
#ifdef SMP
/*
Index: kern/kern_thr.c
===================================================================
--- kern/kern_thr.c (revision 225431)
+++ kern/kern_thr.c (working copy)
@@ -532,9 +532,12 @@
ttd = td;
else
ttd = thread_find(p, uap->id);
- if (ttd != NULL)
+ if (ttd != NULL) {
strcpy(ttd->td_name, name);
- else
+#ifdef KTR
+ sched_clear_tdname(ttd);
+#endif
+ } else
error = ESRCH;
PROC_UNLOCK(p);
return (error);
Index: kern/kern_kthread.c
===================================================================
--- kern/kern_kthread.c (revision 225431)
+++ kern/kern_kthread.c (working copy)
@@ -407,6 +407,9 @@
va_start(ap, fmt);
vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);
va_end(ap);
+#ifdef KTR
+ sched_clear_tdname(td);
+#endif
return (0);
}
va_start(ap, fmt);
Index: kern/sched_4bsd.c
===================================================================
--- kern/sched_4bsd.c (revision 225431)
+++ kern/sched_4bsd.c (working copy)
@@ -1611,7 +1611,18 @@
#endif
}
+#ifdef KTR
void
+sched_clear_tdname(struct thread *td)
+{
+ struct td_sched *ts;
+
+ ts = td->td_sched;
+ ts->ts_name[0] = '\0';
+}
+#endif
+
+void
sched_affinity(struct thread *td)
{
#ifdef SMP
Index: kern/kern_exec.c
===================================================================
--- kern/kern_exec.c (revision 225431)
+++ kern/kern_exec.c (working copy)
@@ -54,6 +54,7 @@
#include <sys/pioctl.h>
#include <sys/namei.h>
#include <sys/resourcevar.h>
+#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/sf_buf.h>
#include <sys/syscallsubr.h>
@@ -609,6 +610,9 @@
else if (vn_commname(binvp, p->p_comm, sizeof(p->p_comm)) != 0)
bcopy(fexecv_proc_title, p->p_comm, sizeof(fexecv_proc_title));
bcopy(p->p_comm, td->td_name, sizeof(td->td_name));
+#ifdef KTR
+ sched_clear_tdname(td);
+#endif
/*
* mark as execed, wakeup the process that vforked (if any) and tell
Index: sys/sched.h
===================================================================
--- sys/sched.h (revision 225431)
+++ sys/sched.h (working copy)
@@ -139,6 +139,9 @@
* functions.
*/
char *sched_tdname(struct thread *td);
+#ifdef KTR
+void sched_clear_tdname(struct thread *td);
+#endif
static __inline void
sched_pin(void)
--
John Baldwin
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