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Has anyone seen performance degradations between 2.2.19 and 2.4.x
when running lmbench? I ran the lmbench benchmark on Linux kernels
2.2.19, 2.4.0, and 2.4.1 and observed performance degradation to be
most noticed in signal handling, pipe latency, file deletion, and
process creation. Are you aware of any kernel changes introduced in
2.4.x that might cause this performance degradation?

The following data are in microseconds, lower is better. Each data point
represents the average of at least four runs.

Tests Linux 2.2.19 Linux 2.4.0 Linux 2.4.1
Signal handler overhead 1.64 3.77 3.82
Pipe latency 4.58 5.28 5.55
File deletion - 10K 11.48 15.30 15.71
Process fork 114.76 140.45 141.98
Process fork+execve 763.57 834.40 840.39

Notes:
1. The benchmark is lmbench-2beta1.
2. The hardware under test is a 700MHz PIII Xeon.
3. The operating system under test is Red Hat 6.2, running Linux kernels 2.2.19,
2.4.0 and 2.4.1, with 4GB memory support.


The following is the summary report generated by the lmbench benchmark.


L M B E N C H 2 . 0 S U M M A R Y
------------------------------------
(Alpha software, do not distribute)

Basic system parameters
----------------------------------------------------
Host OS Description Mhz

--------- ------------- ----------------------- ----
biglinux- Linux 2.2.19 i686-pc-linux-gnu 700
biglinux- Linux 2.2.19 i686-pc-linux-gnu 700
biglinux- Linux 2.2.19 i686-pc-linux-gnu 700
biglinux- Linux 2.2.19 i686-pc-linux-gnu 700
biglinux- Linux 2.4.0 i686-pc-linux-gnu 700
biglinux- Linux 2.4.0 i686-pc-linux-gnu 700
biglinux- Linux 2.4.0 i686-pc-linux-gnu 700
biglinux- Linux 2.4.0 i686-pc-linux-gnu 700
biglinux- Linux 2.4.0 i686-pc-linux-gnu 700
biglinux- Linux 2.4.1 i686-pc-linux-gnu 700
biglinux- Linux 2.4.1 i686-pc-linux-gnu 700
biglinux- Linux 2.4.1 i686-pc-linux-gnu 700
biglinux- Linux 2.4.1 i686-pc-linux-gnu 700

Processor, Processes - times in microseconds - smaller is better
----------------------------------------------------------------
Host OS Mhz null null open selct sig sig fork exec sh
call I/O stat clos TCP inst hndl proc proc proc
--------- ------------- ---- ---- ---- ---- ---- ----- ---- ---- ---- ---- ----
biglinux- Linux 2.2.19 700 0.43 0.61 3.89 4.84 20 1.27 1.64 109 761 2988
biglinux- Linux 2.2.19 700 0.43 0.62 3.91 4.89 20 1.27 1.64 108 760 2981
biglinux- Linux 2.2.19 700 0.43 0.62 3.88 4.93 20 1.27 1.64 108 764 2986
biglinux- Linux 2.2.19 700 0.43 0.62 3.79 4.73 22 1.27 1.64 132 767 3011
biglinux- Linux 2.4.0 700 0.40 0.63 3.37 4.45 19 1.21 3.75 139 831 3219
biglinux- Linux 2.4.0 700 0.40 0.60 3.39 4.46 19 1.24 3.75 139 831 3269
biglinux- Linux 2.4.0 700 0.43 0.63 3.39 4.46 21 1.24 3.82 142 841 3255
biglinux- Linux 2.4.0 700 0.43 0.62 3.37 4.49 21 1.24 3.75 140 835 3244
biglinux- Linux 2.4.0 700 0.43 0.62 3.37 4.47 19 1.24 3.75 140 832 3263
biglinux- Linux 2.4.1 700 0.40 0.61 3.37 4.35 19 1.21 3.80 141 836 3262
biglinux- Linux 2.4.1 700 0.40 0.61 3.39 4.42 21 1.21 3.85 142 841 3316
biglinux- Linux 2.4.1 700 0.40 0.59 3.42 4.38 21 1.21 3.81 141 841 3306
biglinux- Linux 2.4.1 700 0.40 0.61 3.39 4.39 20 1.21 3.81 142 841 3225

Context switching - times in microseconds - smaller is better
-------------------------------------------------------------
Host OS 2p/0K 2p/16K 2p/64K 8p/16K 8p/64K 16p/16K 16p/64K
ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw ctxsw
--------- ------------- ----- ------ ------ ------ ------ ------- -------
biglinux- Linux 2.2.19 0.850 5.0800 21 6.7500 23 8.98000 97
biglinux- Linux 2.2.19 0.860 7.1700 21 6.9200 22 10 138
biglinux- Linux 2.2.19 0.890 6.5100 21 6.5600 136 14 155
biglinux- Linux 2.2.19 0.960 6.4200 21 6.7000 22 7.16000 88
biglinux- Linux 2.4.0 1.040 6.5300 21 6.5800 29 19 185
biglinux- Linux 2.4.0 1.170 6.6200 21 6.7000 22 6.72000 102
biglinux- Linux 2.4.0 1.050 6.6100 21 6.5900 22 6.68000 101
biglinux- Linux 2.4.0 1.070 6.5700 21 6.7200 22 6.79000 102
biglinux- Linux 2.4.0 1.100 6.5300 21 6.5900 22 13 107
biglinux- Linux 2.4.1 1.050 6.4400 21 7.2000 23 6.88000 102
biglinux- Linux 2.4.1 1.140 6.6900 21 6.7100 22 6.92000 103
biglinux- Linux 2.4.1 1.130 6.7200 22 6.9300 22 6.85000 110
biglinux- Linux 2.4.1 1.180 6.5000 21 7.1000 22 7.11000 109

*Local* Communication latencies in microseconds - smaller is better
-------------------------------------------------------------------
Host OS 2p/0K Pipe AF UDP RPC/ TCP RPC/ TCP
ctxsw UNIX UDP TCP conn
--------- ------------- ----- ----- ---- ----- ----- ----- ----- ----
biglinux- Linux 2.2.19 0.850 4.583 8.55 15 25 83
biglinux- Linux 2.2.19 0.860 4.605 8.96 15 25 85
biglinux- Linux 2.2.19 0.890 4.545 8.79 15 25 83
biglinux- Linux 2.2.19 0.960 4.581 8.85 15 25 86
biglinux- Linux 2.4.0 1.040 5.193 8.74 15 22 9.0M
biglinux- Linux 2.4.0 1.170 5.274 8.80 15 22 9.0M
biglinux- Linux 2.4.0 1.050 5.378 9.02 15 23 23M
biglinux- Linux 2.4.0 1.070 5.288 8.99 15 22 3.0M
biglinux- Linux 2.4.0 1.100 5.273 8.81 15 23 29M
biglinux- Linux 2.4.1 1.050 5.291 8.41 15 23 3.0M
biglinux- Linux 2.4.1 1.140 5.419 8.56 15 23 9.0M
biglinux- Linux 2.4.1 1.130 5.574 8.81 15 23 29M
biglinux- Linux 2.4.1 1.180 5.646 9.01 15 24 9.0M

File & VM system latencies in microseconds - smaller is better
--------------------------------------------------------------
Host OS 0K File 10K File Mmap Prot Page
Create Delete Create Delete Latency Fault Fault
--------- ------------- ------ ------ ------ ------ ------- ----- -----
biglinux- Linux 2.2.19 8.8928 0.5667 17 1.1416 24.57400 0.887 528
biglinux- Linux 2.2.19 8.8976 0.5710 17 1.1458 23.76700 0.887 518
biglinux- Linux 2.2.19 8.9103 0.5625 17 1.1297 23.83100 0.887 518
biglinux- Linux 2.2.19 8.8881 0.5617 17 1.1739 23.80700 0.888 519
biglinux- Linux 2.4.0 9.4500 0.5682 19 1.5225 1097 0.847 3.00000
biglinux- Linux 2.4.0 9.4589 0.5707 19 1.5247 1129 0.850 3.00000
biglinux- Linux 2.4.0 9.4545 0.5724 19 1.5279 1108 0.887 3.00000
biglinux- Linux 2.4.0 9.4661 0.5762 19 1.5340 1104 0.854 3.00000
biglinux- Linux 2.4.0 9.4563 0.5781 19 1.5398 1140 0.850 3.00000
biglinux- Linux 2.4.1 9.5905 0.5969 17 1.5588 1138 0.837 3.00000
biglinux- Linux 2.4.1 9.6089 0.6082 17 1.5774 1140 0.862 3.00000
biglinux- Linux 2.4.1 9.5914 0.5986 17 1.5677 1156 0.835 3.00000
biglinux- Linux 2.4.1 9.6015 0.6109 17 1.5816 1151 0.861 3.00000

*Local* Communication bandwidths in MB/s - bigger is better
-----------------------------------------------------------
Host OS Pipe AF TCP File Mmap Bcopy Bcopy Mem Mem
UNIX reread reread (libc) (hand) read write
--------- ------------- ---- ---- ---- ------ ------ ------ ------ ---- -----
biglinux- Linux 2.2.19 684 458 256 219 258 131 129 258 199
biglinux- Linux 2.2.19 684 458 254 191 258 133 130 258 198
biglinux- Linux 2.2.19 685 457 195 219 258 135 129 258 199
biglinux- Linux 2.2.19 694 454 248 219 258 133 129 258 198
biglinux- Linux 2.4.0 651 369 470 146 257 128 129 257 197
biglinux- Linux 2.4.0 641 371 478 209 257 119 129 257 197
biglinux- Linux 2.4.0 647 372 481 209 257 127 128 257 197
biglinux- Linux 2.4.0 634 369 479 209 257 130 129 257 197
biglinux- Linux 2.4.0 641 351 483 210 257 127 129 257 197
biglinux- Linux 2.4.1 650 379 476 209 257 128 129 257 197
biglinux- Linux 2.4.1 622 367 472 209 257 120 128 257 197
biglinux- Linux 2.4.1 615 367 471 209 257 129 129 257 197
biglinux- Linux 2.4.1 624 384 463 209 257 126 129 257 197

Memory latencies in nanoseconds - smaller is better
(WARNING - may not be correct, check graphs)
---------------------------------------------------
Host OS Mhz L1 $ L2 $ Main mem Guesses
--------- ------------- ---- ----- ------ -------- -------
biglinux- Linux 2.2.19 700 4.286 24 201
biglinux- Linux 2.2.19 700 4.286 12 201
biglinux- Linux 2.2.19 700 4.286 12 201
biglinux- Linux 2.2.19 700 4.286 12 201
biglinux- Linux 2.4.0 700 4.286 12 201
biglinux- Linux 2.4.0 700 4.287 12 201
biglinux- Linux 2.4.0 700 4.286 12 201
biglinux- Linux 2.4.0 700 4.287 12 201
biglinux- Linux 2.4.0 700 4.286 12 201
biglinux- Linux 2.4.1 700 4.286 12 201
biglinux- Linux 2.4.1 700 4.287 12 201
biglinux- Linux 2.4.1 700 4.286 12 201
biglinux- Linux 2.4.1 700 4.287 12 201


Cheers .... Duc.

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