slow down in 2.6 vs 2.4

Hello!

Over the last two days I have been struggling with understanding why 2.6.x kernel is slower than 2.4.21/23 kernels. I think I have a test case which demostrates this issue.

I have downloaded gcc-3.4.0 and run with this config:
--enable-languages=c,c++ --prefix=/usr/tmp/foo

using gcc-3.2.3 and binutils-2.13.2.1, on IBM x335 w/2x 2.8G Xeon w/8G RAM, no ht[bios killed], using local file system (XFS):

make times:

2.4.21:
323.68user 56.07system 6:35.77elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (3138783major+3818347minor)pagefaults 0swaps

2.6.7-rc3-s63 (SPA scheduler):
334.01user 69.86system 7:01.47elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (13301major+6931745minor)pagefaults 0swaps

2.6.7-rc3:
336.17user 68.41system 7:02.47elapsed 95%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (13301major+6931745minor)pagefaults 0swaps

Machine:
00:00.0 Host bridge: ServerWorks: Unknown device 0012 (rev 13)
00:00.1 Host bridge: ServerWorks: Unknown device 0012 00:00.2 Host bridge: ServerWorks: Unknown device 0000 00:01.0 VGA compatible controller: ATI Technologies Inc Rage XL (rev 27)
00:0f.0 Host bridge: ServerWorks CSB5 South Bridge (rev 93)
00:0f.1 IDE interface: ServerWorks CSB5 IDE Controller (rev 93)
00:0f.2 USB Controller: ServerWorks OSB4/CSB5 OHCI USB Controller (rev 05)
00:0f.3 ISA bridge: ServerWorks: Unknown device 0225 00:11.0 Host bridge: ServerWorks: Unknown device 0101 (rev 03)
00:11.2 Host bridge: ServerWorks: Unknown device 0101 (rev 03)
01:01.0 SCSI storage controller: Symbios Logic Inc. (formerly NCR): Unknown device 0030 (rev 07) 01:02.0 Ethernet controller: Intel Corporation:
Unknown device 100e (rev 02)
02:01.0 Ethernet controller: BROADCOM Corporation:
Unknown device 16a7 (rev 02)
02:02.0 Ethernet controller: BROADCOM Corporation:
Unknown device 16a7 (rev 02)

Anything else needed? Is there something I can do to try and understand this issue?

Thank you for your time.
Phy

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Phy, you and I have corresponded off list. I think we are experiencing the same thing...

Is there any way to get similar numbers system wide on 2.4? This exists for 2.6.x, and the latest sysstat shows it with sar -B, but as the sar manpage states, the fault/s numbers are not available on 2.4. :(

Stats for a recent period:

Linux 2.4.23 (xxx) 06/09/2004

11:40:00 AM pgpgin/s pgpgout/s fault/s majflt/s

11:50:00 AM     17.52     72.34      0.00      0.00
12:00:00 PM     20.93     65.06      0.00      0.00
Average:        19.22     68.70      0.00      0.00

Linux 2.6.6 (yyy) 06/09/04

11:40:00 pgpgin/s pgpgout/s fault/s majflt/s

11:50:00        70.68     81.13  13756.37      0.02
12:00:00        89.22     81.82  11598.21      0.03
Average:        79.95     81.48  12676.43      0.03

Thats from two different boxes.. see my earlier message this week for an explanation of the setup.

Unfortunately this is common. There are a bunch or tunables like swappiness and readahead you can adjust, but if anyone has a handle on why it's really so slow they don't seem to have gotten a patch out.

On features 2.6 wins, on performance 2.4 seems faster in many cases.

   -bill davidsen ([email protected])
"The secret to procrastination is to put things off until the
 last possible moment - but no longer"  -me