Author: cperciva
Date: Thu Jul 30 04:01:00 2015
New Revision: 286063
URL: https://svnweb.freebsd.org/changeset/base/286063
Log:
Disable blkif indirect segment I/Os in EC2 by default due to performance
issues on some EC2 instance types. Users may want to experiment with
removing this from loader.conf and measuring the performance impact on
the EC2 instances they are using.
Modified:
head/release/tools/ec2.conf
Modified: head/release/tools/ec2.conf
==============================================================================
--- head/release/tools/ec2.conf Thu Jul 30 03:50:01 2015 (r286062)
+++ head/release/tools/ec2.conf Thu Jul 30 04:01:00 2015 (r286063)
@@ -70,6 +70,11 @@ vm_extra_pre_umount() {
# nodes, but apply the workaround just in case.
echo 'hw.broken_txfifo="1"' >> ${DESTDIR}/boot/loader.conf
+ # Some EC2 instances suffer a significant (~40%) reduction in
+ # throughput when using blkif indirect segment I/Os. Disable this
+ # by default for now.
+ echo 'hw.xbd.xbd_enable_indirect="0"' >> ${DESTDIR}/boot/loader.conf
+
# The first time the AMI boots, the installed "first boot" scripts
# should be allowed to run:
# * ec2_configinit (download and process EC2 user-data)
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