Source-Changes-HG archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

[src/trunk]: src/sys/kern optionally use FUA instead of full cache sync, and ...



details:   https://anonhg.NetBSD.org/src/rev/664601343aac
branches:  trunk
changeset: 352505:664601343aac
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Wed Apr 05 20:38:53 2017 +0000

description:
optionally use FUA instead of full cache sync, and DPO for journal writes,
when supported by disk device; controlled by sysctl vfs.wapbl.allow_fuadpo,
default off for now

discussed on tech-kern

diffstat:

 sys/kern/vfs_wapbl.c |  79 ++++++++++++++++++++++++++++++++++++++++++++++-----
 1 files changed, 70 insertions(+), 9 deletions(-)

diffs (187 lines):

diff -r 79b89582b86e -r 664601343aac sys/kern/vfs_wapbl.c
--- a/sys/kern/vfs_wapbl.c      Wed Apr 05 20:30:55 2017 +0000
+++ b/sys/kern/vfs_wapbl.c      Wed Apr 05 20:38:53 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_wapbl.c,v 1.92 2017/03/17 03:19:46 riastradh Exp $ */
+/*     $NetBSD: vfs_wapbl.c,v 1.93 2017/04/05 20:38:53 jdolecek Exp $  */
 
 /*-
  * Copyright (c) 2003, 2008, 2009 The NetBSD Foundation, Inc.
@@ -36,7 +36,7 @@
 #define WAPBL_INTERNAL
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_wapbl.c,v 1.92 2017/03/17 03:19:46 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_wapbl.c,v 1.93 2017/04/05 20:38:53 jdolecek Exp $");
 
 #include <sys/param.h>
 #include <sys/bitops.h>
@@ -71,6 +71,7 @@
 static struct sysctllog *wapbl_sysctl;
 static int wapbl_flush_disk_cache = 1;
 static int wapbl_verbose_commit = 0;
+static int wapbl_allow_fuadpo = 0;     /* switched off by default for now */
 
 static inline size_t wapbl_space_free(size_t, off_t, off_t);
 
@@ -230,6 +231,16 @@
        u_char *wl_buffer;      /* l:   buffer for wapbl_buffered_write() */
        daddr_t wl_buffer_dblk; /* l:   buffer disk block address */
        size_t wl_buffer_used;  /* l:   buffer current use */
+
+       int wl_dkcache;         /* r:   disk cache flags */
+#define WAPBL_USE_FUA(wl)      \
+               (wapbl_allow_fuadpo && ISSET((wl)->wl_dkcache, DKCACHE_FUA))
+#define WAPBL_JFLAGS(wl)       \
+               (WAPBL_USE_FUA(wl) ? (wl)->wl_jwrite_flags : 0)
+#define WAPBL_MFLAGS(wl)       \
+               (WAPBL_USE_FUA(wl) ? (wl)->wl_mwrite_flags : 0)
+       int wl_jwrite_flags;    /* r:   journal write flags */
+       int wl_mwrite_flags;    /* r:   metadata write flags */
 };
 
 #ifdef WAPBL_DEBUG_PRINT
@@ -281,6 +292,8 @@
 static void wapbl_evcnt_init(struct wapbl *);
 static void wapbl_evcnt_free(struct wapbl *);
 
+static void wapbl_dkcache_init(struct wapbl *);
+
 #if 0
 int wapbl_replay_verify(struct wapbl_replay *, struct vnode *);
 #endif
@@ -335,6 +348,18 @@
                       SYSCTL_DESCR("show time and size of wapbl log commits"),
                       NULL, 0, &wapbl_verbose_commit, 0,
                       CTL_CREATE, CTL_EOL);
+       if (rv)
+               return rv;
+
+       rv = sysctl_createv(&wapbl_sysctl, 0, &rnode, &cnode,
+                      CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
+                      CTLTYPE_INT, "allow_fuadpo",
+                      SYSCTL_DESCR("allow use of FUA/DPO instead of cash flush if available"),
+                      NULL, 0, &wapbl_allow_fuadpo, 0,
+                      CTL_CREATE, CTL_EOL);
+       if (rv)
+               return rv;
+
        return rv;
 }
 
@@ -391,6 +416,30 @@
        evcnt_detach(&wl->wl_ev_cacheflush);
 }
 
+static void
+wapbl_dkcache_init(struct wapbl *wl)
+{
+       int error;
+
+       /* Get disk cache flags */
+       error = VOP_IOCTL(wl->wl_devvp, DIOCGCACHE, &wl->wl_dkcache,
+           FWRITE, FSCRED);
+       if (error) {
+               /* behave as if there was a write cache */
+               wl->wl_dkcache = DKCACHE_WRITE;
+       }
+
+       /* Use FUA instead of cache flush if available */
+       if (ISSET(wl->wl_dkcache, DKCACHE_FUA)) {
+               wl->wl_jwrite_flags |= B_MEDIA_FUA;
+               wl->wl_mwrite_flags |= B_MEDIA_FUA;
+       }
+
+       /* Use DPO for journal writes if available */
+       if (ISSET(wl->wl_dkcache, DKCACHE_DPO))
+               wl->wl_jwrite_flags |= B_MEDIA_DPO;
+}
+
 static int
 wapbl_start_flush_inodes(struct wapbl *wl, struct wapbl_replay *wr)
 {
@@ -563,6 +612,8 @@
 
        wapbl_evcnt_init(wl);
 
+       wapbl_dkcache_init(wl);
+
        /* Initialize the commit header */
        {
                struct wapbl_wc_header *wc;
@@ -809,7 +860,6 @@
        struct buf *bp;
        int error;
 
-       KASSERT((flags & ~(B_WRITE | B_READ)) == 0);
        KASSERT(devvp->v_type == VBLK);
 
        if ((flags & (B_WRITE | B_READ)) == B_WRITE) {
@@ -823,7 +873,7 @@
 
        bp = getiobuf(devvp, true);
        bp->b_flags = flags;
-       bp->b_cflags = BC_BUSY; /* silly & dubious */
+       bp->b_cflags = BC_BUSY; /* mandatory, asserted by biowait() */
        bp->b_dev = devvp->v_rdev;
        bp->b_data = data;
        bp->b_bufsize = bp->b_resid = bp->b_bcount = len;
@@ -898,7 +948,8 @@
                return 0;
 
        error = wapbl_doio(wl->wl_buffer, wl->wl_buffer_used,
-           wl->wl_devvp, wl->wl_buffer_dblk, B_WRITE);
+           wl->wl_devvp, wl->wl_buffer_dblk,
+           B_WRITE | WAPBL_JFLAGS(wl));
        wl->wl_buffer_used = 0;
 
        wl->wl_ev_journalwrite.ev_count++;
@@ -948,12 +999,10 @@
        if (len >= resid) {
                memcpy(wl->wl_buffer + wl->wl_buffer_used, data, resid);
                wl->wl_buffer_used += resid;
-               error = wapbl_doio(wl->wl_buffer, wl->wl_buffer_used,
-                   wl->wl_devvp, wl->wl_buffer_dblk, B_WRITE);
+               error = wapbl_buffered_flush(wl);
                data = (uint8_t *)data + resid;
                len -= resid;
                wl->wl_buffer_dblk = pbn + btodb(resid);
-               wl->wl_buffer_used = 0;
                if (error)
                        return error;
        }
@@ -1500,6 +1549,13 @@
        }
 
        /*
+        * Make sure that the buf doesn't retain the media flags, so that
+        * e.g. wapbl_allow_fuadpo has immediate effect on any following I/O.
+        * The flags will be set again if needed by another I/O.
+        */
+       bp->b_flags &= ~B_MEDIA_FLAGS;
+
+       /*
         * Release the buffer here. wapbl_flush() may wait for the
         * log to become empty and we better unbusy the buffer before
         * wapbl_flush() returns.
@@ -1754,6 +1810,10 @@
                }
                bp->b_iodone = wapbl_biodone;
                bp->b_private = we;
+
+               /* make sure the block is saved sync when FUA in use */
+               bp->b_flags |= WAPBL_MFLAGS(wl);
+
                bremfree(bp);
                wapbl_remove_buf_locked(wl, bp);
                mutex_exit(&wl->wl_mtx);
@@ -2201,7 +2261,8 @@
        int force = 1;
        int error;
 
-       if (!wapbl_flush_disk_cache) {
+       /* Skip full cache sync if disabled, or when using FUA */
+       if (!wapbl_flush_disk_cache || WAPBL_USE_FUA(wl)) {
                return 0;
        }
        if (verbose) {



Home | Main Index | Thread Index | Old Index