[src/trunk]: src/sys/kern Buffer cache SDT probes.

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e1cf61cca7f1
branches:  trunk
changeset: 745007:e1cf61cca7f1
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Thu Feb 20 15:48:38 2020 +0000

description:
Buffer cache SDT probes.

diffstat:

 sys/kern/vfs_bio.c |  61 ++++++++++++++++++++++++++++++++++++++++++++---------
 1 files changed, 50 insertions(+), 11 deletions(-)

diffs (174 lines):

diff -r 5208f65bbc4e -r e1cf61cca7f1 sys/kern/vfs_bio.c
--- a/sys/kern/vfs_bio.c        Thu Feb 20 15:48:05 2020 +0000
+++ b/sys/kern/vfs_bio.c        Thu Feb 20 15:48:38 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_bio.c,v 1.287 2020/01/17 19:33:14 ad Exp $ */
+/*     $NetBSD: vfs_bio.c,v 1.288 2020/02/20 15:48:38 riastradh Exp $  */
 
 /*-
  * Copyright (c) 2007, 2008, 2009, 2019 The NetBSD Foundation, Inc.
@@ -123,7 +123,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.287 2020/01/17 19:33:14 ad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 1.288 2020/02/20 15:48:38 riastradh Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_bufcache.h"
@@ -154,6 +154,28 @@
 
 #include <miscfs/specfs/specdev.h>
 
+SDT_PROVIDER_DEFINE(io);
+
+SDT_PROBE_DEFINE4(io, kernel, , bbusy__start,
+    "struct buf *"/*bp*/,
+    "bool"/*intr*/, "int"/*timo*/, "kmutex_t *"/*interlock*/);
+SDT_PROBE_DEFINE5(io, kernel, , bbusy__done,
+    "struct buf *"/*bp*/,
+    "bool"/*intr*/,
+    "int"/*timo*/,
+    "kmutex_t *"/*interlock*/,
+    "int"/*error*/);
+SDT_PROBE_DEFINE0(io, kernel, , getnewbuf__start);
+SDT_PROBE_DEFINE1(io, kernel, , getnewbuf__done,  "struct buf *"/*bp*/);
+SDT_PROBE_DEFINE3(io, kernel, , getblk__start,
+    "struct vnode *"/*vp*/, "daddr_t"/*blkno*/, "int"/*size*/);
+SDT_PROBE_DEFINE4(io, kernel, , getblk__done,
+    "struct vnode *"/*vp*/, "daddr_t"/*blkno*/, "int"/*size*/,
+    "struct buf *"/*bp*/);
+SDT_PROBE_DEFINE2(io, kernel, , brelse, "struct buf *"/*bp*/, "int"/*set*/);
+SDT_PROBE_DEFINE1(io, kernel, , wait__start, "struct buf *"/*bp*/);
+SDT_PROBE_DEFINE1(io, kernel, , wait__done, "struct buf *"/*bp*/);
+
 #ifndef        BUFPAGES
 # define BUFPAGES 0
 #endif
@@ -1027,6 +1049,8 @@
        struct bqueue *bufq;
        struct vnode *vp;
 
+       SDT_PROBE2(io, kernel, , brelse,  bp, set);
+
        KASSERT(bp != NULL);
        KASSERT(mutex_owned(&bufcache_lock));
        KASSERT(!cv_has_waiters(&bp->b_done));
@@ -1211,6 +1235,7 @@
        buf_t *bp;
 
        mutex_enter(&bufcache_lock);
+       SDT_PROBE3(io, kernel, , getblk__start,  vp, blkno, size);
  loop:
        bp = incore(vp, blkno);
        if (bp != NULL) {
@@ -1219,6 +1244,8 @@
                        if (err == EPASSTHROUGH)
                                goto loop;
                        mutex_exit(&bufcache_lock);
+                       SDT_PROBE4(io, kernel, , getblk__done,
+                           vp, blkno, size, NULL);
                        return (NULL);
                }
                KASSERT(!cv_has_waiters(&bp->b_done));
@@ -1260,10 +1287,13 @@
                        LIST_REMOVE(bp, b_hash);
                        brelsel(bp, BC_INVAL);
                        mutex_exit(&bufcache_lock);
+                       SDT_PROBE4(io, kernel, , getblk__done,
+                           vp, blkno, size, NULL);
                        return NULL;
                }
        }
        BIO_SETPRIO(bp, BPRIO_DEFAULT);
+       SDT_PROBE4(io, kernel, , getblk__done,  vp, blkno, size, bp);
        return (bp);
 }
 
@@ -1382,6 +1412,8 @@
        struct vnode *vp;
        struct mount *transmp = NULL;
 
+       SDT_PROBE0(io, kernel, , getnewbuf__start);
+
  start:
        KASSERT(mutex_owned(&bufcache_lock));
 
@@ -1399,6 +1431,7 @@
 #if defined(DIAGNOSTIC)
                        bp->b_freelistindex = -1;
 #endif /* defined(DIAGNOSTIC) */
+                       SDT_PROBE1(io, kernel, , getnewbuf__done,  bp);
                        return (bp);
                }
                mutex_enter(&bufcache_lock);
@@ -1441,6 +1474,7 @@
                                (void)cv_timedwait(&needbuffer_cv,
                                    &bufcache_lock, slptimeo);
                }
+               SDT_PROBE1(io, kernel, , getnewbuf__done,  NULL);
                return (NULL);
        }
 
@@ -1479,6 +1513,7 @@
                KASSERT(transmp != NULL);
                fstrans_done(transmp);
                mutex_enter(&bufcache_lock);
+               SDT_PROBE1(io, kernel, , getnewbuf__done,  NULL);
                return (NULL);
        }
 
@@ -1508,6 +1543,7 @@
                mutex_exit(vp->v_interlock);
        }
 
+       SDT_PROBE1(io, kernel, , getnewbuf__done,  bp);
        return (bp);
 }
 
@@ -1557,11 +1593,6 @@
        return size;
 }
 
-SDT_PROVIDER_DEFINE(io);
-
-SDT_PROBE_DEFINE1(io, kernel, , wait__start, "struct buf *"/*bp*/);
-SDT_PROBE_DEFINE1(io, kernel, , wait__done, "struct buf *"/*bp*/);
-
 /*
  * Wait for operations on the buffer to complete.
  * When they do, extract and return the I/O's error value.
@@ -2163,9 +2194,13 @@
 
        KASSERT(mutex_owned(&bufcache_lock));
 
+       SDT_PROBE4(io, kernel, , bbusy__start,  bp, intr, timo, interlock);
+
        if ((bp->b_cflags & BC_BUSY) != 0) {
-               if (curlwp == uvm.pagedaemon_lwp)
-                       return EDEADLK;
+               if (curlwp == uvm.pagedaemon_lwp) {
+                       error = EDEADLK;
+                       goto out;
+               }
                bp->b_cflags |= BC_WANTED;
                bref(bp);
                if (interlock != NULL)
@@ -2181,11 +2216,15 @@
                if (interlock != NULL)
                        mutex_enter(interlock);
                if (error != 0)
-                       return error;
-               return EPASSTHROUGH;
+                       goto out;
+               error = EPASSTHROUGH;
+               goto out;
        }
        bp->b_cflags |= BC_BUSY;
+       error = 0;
 
+out:   SDT_PROBE5(io, kernel, , bbusy__done,
+           bp, intr, timo, interlock, error);
        return 0;
 }