Author: cperciva
Date: Wed Jun 29 23:56:24 2016
New Revision: 302288
URL: https://svnweb.freebsd.org/changeset/base/302288
Log:
Enable indirect segment I/Os by default in the Xen blkfront driver when
running on EC2. Due to improvements in EC2, the performance penalty which
was present on some EC2 instances no longer exists, and enabling this
feature now consistently yields ~20% higher throughput with equal or lower
latency.
Reverts: r286063
Approved by: re (gjb)
MFC after: 2 weeks
Relnotes: Improved disk throughput on EC2
Modified:
head/release/tools/ec2.conf
Modified: head/release/tools/ec2.conf
==============================================================================
--- head/release/tools/ec2.conf Wed Jun 29 23:33:44 2016 (r302287)
+++ head/release/tools/ec2.conf Wed Jun 29 23:56:24 2016 (r302288)
@@ -72,11 +72,6 @@ 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
-
# Some EC2 instances run on a version of Xen which has a bug relating
# to the migration of MSI-X interrupts; this is visible as SR-IOV
# networking (aka. "EC2 Enhanced Networking") not being able to pass
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