From a5c1653b5c48a9d59acc372d500d6a79abec019d Mon Sep 17 00:00:00 2001 From: Colin Percival Date: Thu, 30 Jul 2015 04:01:00 +0000 Subject: [PATCH] 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. --- release/tools/ec2.conf | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/release/tools/ec2.conf b/release/tools/ec2.conf index 9472ec59d89f..557e60260dbf 100644 --- a/release/tools/ec2.conf +++ b/release/tools/ec2.conf @@ -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)