diff options
author | dillon <dillon@FreeBSD.org> | 2000-01-05 05:11:37 +0000 |
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committer | dillon <dillon@FreeBSD.org> | 2000-01-05 05:11:37 +0000 |
commit | c6689c797daca2e96b0ccaf727e86ebf09e00e37 (patch) | |
tree | 5cdfd2f2b906cb0407fd5a329f091623735a9701 /sys/kern/vfs_export.c | |
parent | e112622878175672c0eaa5a87ccdf0e882ccc784 (diff) | |
download | FreeBSD-src-c6689c797daca2e96b0ccaf727e86ebf09e00e37.zip FreeBSD-src-c6689c797daca2e96b0ccaf727e86ebf09e00e37.tar.gz |
Enhance reassignbuf(). When a buffer cannot be time-optimally inserted
into vnode dirtyblkhd we append it to the list instead of prepend it to
the list in order to maintain a 'forward' locality of reference, which
is arguably better then 'reverse'. The original algorithm did things this
way to but at a huge time cost.
Enhance the append interlock for NFS writes to handle intr/soft mounts
better.
Fix the hysteresis for NFS async daemon I/O requests to reduce the
number of unnecessary context switches.
Modify handling of NFS mount options. Any given user option that is
too high now defaults to the kernel maximum for that option rather then
the kernel default for that option.
Reviewed by: Alfred Perlstein <bright@wintelcom.net>
Diffstat (limited to 'sys/kern/vfs_export.c')
-rw-r--r-- | sys/kern/vfs_export.c | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/sys/kern/vfs_export.c b/sys/kern/vfs_export.c index 76bd584..059ca2a 100644 --- a/sys/kern/vfs_export.c +++ b/sys/kern/vfs_export.c @@ -1208,6 +1208,7 @@ reassignbuf(bp, newvp) tbp = TAILQ_FIRST(listheadp); if (tbp == NULL || bp->b_lblkno == 0 || + (bp->b_lblkno > 0 && tbp->b_lblkno < 0) || (bp->b_lblkno > 0 && bp->b_lblkno < tbp->b_lblkno)) { TAILQ_INSERT_HEAD(listheadp, bp, b_vnbufs); ++reassignbufsortgood; @@ -1217,14 +1218,30 @@ reassignbuf(bp, newvp) } else if (reassignbufmethod == 1) { /* * New sorting algorithm, only handle sequential case, - * otherwise guess. + * otherwise append to end (but before metadata) */ if ((tbp = gbincore(newvp, bp->b_lblkno - 1)) != NULL && (tbp->b_xflags & BX_VNDIRTY)) { + /* + * Found the best place to insert the buffer + */ TAILQ_INSERT_AFTER(listheadp, tbp, bp, b_vnbufs); ++reassignbufsortgood; } else { - TAILQ_INSERT_HEAD(listheadp, bp, b_vnbufs); + /* + * Missed, append to end, but before meta-data. + * We know that the head buffer in the list is + * not meta-data due to prior conditionals. + * + * Indirect effects: NFS second stage write + * tends to wind up here, giving maximum + * distance between the unstable write and the + * commit rpc. + */ + tbp = TAILQ_LAST(listheadp, buflists); + while (tbp && tbp->b_lblkno < 0) + tbp = TAILQ_PREV(tbp, buflists, b_vnbufs); + TAILQ_INSERT_AFTER(listheadp, tbp, bp, b_vnbufs); ++reassignbufsortbad; } } else { |