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Message #01247
[Bug 709245] Re: ARM SMP scheduler performance bug
I ran iperf as well and got poor results with both 256KB and 16Bytes
(2KB).
(desktop-pc) $ iperf -s -w 256K
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 256 KByte (WARNING: requested 256 KByte)
------------------------------------------------------------
[ 4] local 192.168.50.223 port 5001 connected with 192.168.50.107 port 39723
(panda) # iperf -c 192.168.50.223 -w 256K -t 10
------------------------------------------------------------
Client connecting to 192.168.50.223, TCP port 5001
TCP window size: 256 KByte (WARNING: requested 256 KByte)
------------------------------------------------------------
[ 3] local 192.168.50.107 port 39723 connected with 192.168.50.223 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-13.3 sec 200 KBytes 123 Kbits/sec
(desktop-pc) $ iperf -s -w 16
WARNING: TCP window size set to 16 bytes. A small window size
will give poor performance. See the Iperf documentation.
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 2.23 KByte (WARNING: requested 16.0 Byte)
------------------------------------------------------------
[ 4] local 192.168.50.223 port 5001 connected with 192.168.50.107 port 39724
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-18.3 sec 144 KBytes 64.5 Kbits/sec
(panda) # iperf -c 192.168.50.223 -w 16 -t 10
WARNING: TCP window size set to 16 bytes. A small window size
will give poor performance. See the Iperf documentation.
------------------------------------------------------------
Client connecting to 192.168.50.223, TCP port 5001
TCP window size: 2.00 KByte (WARNING: requested 16.0 Byte)
------------------------------------------------------------
[ 3] local 192.168.50.107 port 39724 connected with 192.168.50.223 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-18.3 sec 144 KBytes 64.5 Kbits/sec
--
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https://bugs.launchpad.net/bugs/709245
Title:
ARM SMP scheduler performance bug
Status in Linaro Ubuntu Evaluation Builds:
Fix Released
Status in Linaro Linux:
Fix Committed
Status in OEM Priority Project:
Fix Released
Status in OEM Priority Project maverick series:
Fix Released
Status in OEM Priority Project natty series:
Fix Released
Status in OEM Priority Project oneiric series:
Fix Released
Status in “linux-ti-omap4” package in Ubuntu:
Fix Released
Status in “linux-ti-omap4” source package in Maverick:
Fix Released
Status in “linux-ti-omap4” source package in Natty:
Fix Released
Status in “linux-ti-omap4” source package in Oneiric:
Fix Released
Bug description:
Original Bug name: "panda: USB disk IO slow"
This bug effects ARM Cortex A9 cores, snowball, nvidia, OMAP 4, and
other Cortex A9 processors. Problem is in Fedora ARM builds also so
not limited to Ubuntu.
My Panda's USB seems to be significantly slower than a Beagle C4.
hdparm shows buffered reads as ~12MB/s on the Panda, and about ~20-25MB/s on a Beagle C4 from the same
external Lacie USB disk.
Kernel is 2.6.37-1002-linaro-omap
Disk shows as:
[ 5.170440] scsi 0:0:0:0: Direct-Access LaCie d2 quadra PQ: 0 ANSI: 4
[ 5.172546] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 5.175415] sd 0:0:0:0: [sda] 976773168 512-byte logical blocks: (500 GB/465 GiB)
The board is otherwise idle during the test.
Doing perf_2.6.37-12 record -a dd if=/dev/sda of=/dev/null bs=4096
count=100000
shows :
81.41% swapper [kernel.kallsyms] [k] default_idle
6.33% dd [kernel.kallsyms] [k] __copy_to_user
0.94% swapper [kernel.kallsyms] [k] cpu_idle
0.51% dd [kernel.kallsyms] [k] __make_request
0.51% perf_2.6.37-12 [kernel.kallsyms] [k] __copy_from_user
which suggests it's not CPU constrained.
Dave
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