ARM SMP scheduler performance bug
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
Linaro Linux |
Fix Released
|
Medium
|
Unassigned | ||
Linaro Ubuntu |
Fix Released
|
High
|
John Rigby | ||
OEM Priority Project |
Fix Released
|
High
|
Unassigned | ||
Maverick |
Fix Released
|
Undecided
|
Unassigned | ||
Natty |
Fix Released
|
Undecided
|
Unassigned | ||
Oneiric |
Fix Released
|
Undecided
|
Unassigned | ||
linux-ti-omap4 (Ubuntu) |
Fix Released
|
High
|
Ming Lei | ||
Maverick |
Fix Released
|
High
|
Unassigned | ||
Natty |
Fix Released
|
High
|
Unassigned | ||
Oneiric |
Fix Released
|
High
|
Ming Lei |
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-
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
Changed in linux-linaro: | |
importance: | Undecided → Medium |
Changed in linux-linaro: | |
assignee: | nobody → Mian Yousaf Kaukab (mian-yousaf-kaukab) |
Changed in linux-linaro: | |
status: | New → Confirmed |
Changed in linux-ti-omap4 (Ubuntu): | |
importance: | Undecided → High |
status: | New → Confirmed |
Changed in linaro-ubuntu: | |
milestone: | none → 11.07 |
tags: | added: armel kernel-bug |
tags: | added: iso-testing |
description: | updated |
summary: |
- panda: USB disk IO slow + ARM SMP scheduler performance bug |
Changed in linaro-ubuntu: | |
milestone: | 11.07 → 11.08 |
Changed in linux-ti-omap4 (Ubuntu Natty): | |
status: | New → Confirmed |
Changed in linux-ti-omap4 (Ubuntu Maverick): | |
status: | New → Confirmed |
importance: | Undecided → High |
Changed in linux-ti-omap4 (Ubuntu Natty): | |
importance: | Undecided → High |
Changed in oem-priority: | |
importance: | Undecided → High |
description: | updated |
tags: | added: patch |
Changed in linaro-ubuntu: | |
milestone: | 11.08 → 11.09 |
Changed in linaro-ubuntu: | |
assignee: | nobody → John Rigby (jcrigby) |
tags: | added: rls-mgr-o-tracking |
Changed in linux-ti-omap4 (Ubuntu Maverick): | |
status: | Confirmed → Fix Committed |
Changed in linux-ti-omap4 (Ubuntu Natty): | |
status: | Confirmed → Fix Committed |
Changed in oem-priority: | |
status: | New → Fix Committed |
Changed in linaro-ubuntu: | |
status: | Confirmed → Fix Committed |
Changed in linux-linaro: | |
status: | Confirmed → Fix Committed |
Changed in linaro-ubuntu: | |
status: | Fix Committed → Fix Released |
Changed in oem-priority: | |
status: | Fix Committed → Fix Released |
Changed in linux-linaro: | |
assignee: | Mian Yousaf Kaukab (mian-yousaf-kaukab) → nobody |
status: | Fix Committed → Fix Released |
Slower on 2.6.38-1000:
/dev/sda:
Timing cached reads: 436 MB in 2.00 seconds = 218.03 MB/sec
Timing buffered disk reads: 20 MB in 3.23 seconds = 6.19 MB/sec