>Number: 145395
>Category: bin
>Synopsis: [nanobsd] [patch] Extremely slow nanobsd disk image creation
>and 100% disk load on zfs
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Apr 04 23:00:13 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator: Alex Bakhtin
>Release: 8.0-STABLE
>Organization:
>Environment:
FreeBSD tarzan-new.private.flydrag.ru 8.0-STABLE FreeBSD 8.0-STABLE #1: Sat Apr
3 04:54:06 UTC 2010
bakh...@tarzan-new.private.flydrag.ru:/mnt/obj/usr/src.old/sys/DEBUG amd64
>Description:
Extremely slow nanobsd disk image creation discovered on zfs.
Image write speed is near 1 Megabyte/sec with 100% load of all zfs vdevs.
This is because default -o sync behavior of mdconfig causing zfs to syncronize
on every write.
I think the best way to fix this is to provide an option in nanobsd.sh to allow
user to switch to async mode (and use sync by default - POLA):
# Use -o async option for mdconfig
NANO_MD_ASYNC=0
After applying this patch image write speed is near 30 megs/sec on my HW.
>How-To-Repeat:
set NANO_OBJ to some zfs file system
check image creation/partition duplication speed and disk load (f.e. using
gstat).
>Fix:
Patch attached with submission follows:
--- /usr/src/tools/tools/nanobsd/nanobsd.sh 2010-04-02 03:42:47.000000000
+0000
+++ nanobsd.sh 2010-04-05 06:43:41.000000000 +0000
@@ -128,6 +128,9 @@
# Can be "file" or "swap"
NANO_MD_BACKING="file"
+# Use -o async option for mdconfig
+NANO_MD_ASYNC=0
+
# Progress Print level
PPLEVEL=3
@@ -428,6 +431,11 @@
MNT=${NANO_OBJ}/_.mnt
mkdir -p ${MNT}
+ _NANO_MDCONFIG_OPTIONS=' '
+ if [ "${NANO_MD_ASYNC}" == 1 ] ; then
+ _NANO_MDCONFIG_OPTIONS="-o async"
+ fi
+
if [ "${NANO_MD_BACKING}" = "swap" ] ; then
MD=`mdconfig -a -t swap -s ${NANO_MEDIASIZE} -x ${NANO_SECTS} \
-y ${NANO_HEADS}`
@@ -436,7 +444,7 @@
dd if=/dev/zero of=${IMG} bs=${NANO_SECTS}b \
count=`expr ${NANO_MEDIASIZE} / ${NANO_SECTS}`
MD=`mdconfig -a -t vnode -f ${IMG} -x ${NANO_SECTS} \
- -y ${NANO_HEADS}`
+ -y ${NANO_HEADS} ${_NANO_MDCONFIG_OPTIONS}`
fi
trap "echo 'Running exit trap code' ; df -i ${MNT} ; umount ${MNT} ||
true ; mdconfig -d -u $MD" 1 2 15 EXIT
>Release-Note:
>Audit-Trail:
>Unformatted:
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