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Enable indirect segment I/Os by default in the Xen blkfront driver when

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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
This commit is contained in:
Colin Percival 2016-06-29 23:56:24 +00:00
parent 4b61754c68
commit 4d1afa14d5
1 changed files with 0 additions and 5 deletions
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5
release/tools/ec2.conf
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@ -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