[Bug 277225] emulators/xen-kernel - poor disk performance
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Date: Thu, 22 Feb 2024 17:18:08 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=277225
Bug ID: 277225
Summary: emulators/xen-kernel - poor disk performance
Product: Ports & Packages
Version: Latest
Hardware: Any
OS: Any
Status: New
Severity: Affects Only Me
Priority: ---
Component: Individual Port(s)
Assignee: royger@freebsd.org
Reporter: mgrooms@shrew.net
Flags: maintainer-feedback?(royger@freebsd.org)
Assignee: royger@freebsd.org
I've been doing some testing with Xen using a FreeBSD as a control domain and
have observed a dramatic difference between dom0 disk performance and domU.
Here is what I'm using as a testbed:
Xeon 8336 ( 32c/64t )
256G 3200mhz ECC RAM
16x SSD in RAID10
The difference between dom0 and bare metal disk I/O is pretty much the same so
I didn't bother including it here. However, a single domU only seems to perform
at around 10% the speed of the dom0 ...
FreeBSD 13.2 Dom0 - UFS
--------------------------------------------------------------------------------
Version 1.98 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
test2.shrew.lab 32G 745k 99 1.5g 98 1.1g 75 1985k 98 1.3g 48 +++++ +++
Latency 11285us 8916us 539ms 8359us 464ms 4482us
Version 1.98 ------Sequential Create------ --------Random Create--------
test2.shrew.lab -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 39572us 20us 28us 24095us 15us 25us
FreeBSD 13.2 Dom0 - ZFS
--------------------------------------------------------------------------------
Version 1.98 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
test2.shrew.lab 32G 301k 99 1.2g 88 842m 94 673k 99 1.8g 98 +++++ +++
Latency 26165us 134ms 11993us 12551us 5559us 4839us
Version 1.98 ------Sequential Create------ --------Random Create--------
test2.shrew.lab -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ 25662.595077 49 +++++ +++ +++++ +++
+++++ +++
Latency 1878us 61us 315ms 1811us 22us 2567us
Rocky Linux 9.3 DomU - UFS img
--------------------------------------------------------------------------------
Version 2.00 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
linux2.shrew.la 31G 1294k 97 112m 5 89.7m 6 2421k 98 159m 7 3009 76
Latency 6158us 12484us 31509us 3993us 9576us 33077us
Version 2.00 ------Sequential Create------ --------Random Create--------
linux2.shrew.lab -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 678us 561us 533us 737us 15us 587us
Rocky Linux 9.3 DomU - ZFS img
--------------------------------------------------------------------------------
Delete files in random order...done.
Version 2.00 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
linux3.shrew.la 31G 1307k 98 145m 7 98.8m 7 2389k 98 196m 9 2584 66
Latency 6420us 15877us 132ms 4481us 5128us 28223us
Version 2.00 ------Sequential Create------ --------Random Create--------
linux3.shrew.lab -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 926us 102us 287us 996us 162us 571us
FreeBSD 14 DomU - UFS img
--------------------------------------------------------------------------------
Version 1.98 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
freebsd2.shrew. 32G 748k 5 195m 0 87.9m 0 1991k 13 151m 0 3845 0
Latency 11178us 93012us 43601us 8594us 30453us 159ms
Version 1.98 ------Sequential Create------ --------Random Create--------
freebsd2.shrew.lab -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 38388us 17us 20us 37807us 13us 19us
FreeBSD 14 DomU - ZFS img
--------------------------------------------------------------------------------
Version 1.98 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Name:Size etc /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
freebsd3.shrew. 32G 750k 4 189m 0 95.6m 0 2043k 9 188m 0 2446 1
Latency 11275us 211ms 160ms 8840us 28129us 323ms
Version 1.98 ------Sequential Create------ --------Random Create--------
freebsd3.shrew.lab -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
Latency 39562us 14us 19us 36463us 14us 25us
I assumed there would be overhead but 1/10th the performance doesn't feel
right. Is there a problem here or are my expectations just way off?
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