Andrew,
I got 5250 Req/s with your locks-sem.patch on normal Apache.
It is good performance on normal Apache.

Andrew Morton writes:
 > Kouichi, could you please test the performance of this on
 > your 8-way with Apache+fcntl serialisation? (the normal
 > Apache).  Please use 2.4.0-test10-pre5, not 2.4.0-test10.
 > Something has gone funny with test10 and I'm getting much
 > lower rates.

Followings are the recent data with/without serialization.

                        w/ serialize    w/o serialize
240t10pre5              2237            5358
240t10pre5+P2           5253            5355**
240t10pre5+P3           ---             NG
240t10pre5+locksem      5250            ---
        **: once we found deadlock
        NG: cannot complete measurement
        --: we've not measured.

Normal apache on various kernel setting as follows:

> test8                 5287 <-- best performance
> test10-pre5+P2        5258
> 240t10pre5+locksem    5250
> test9+P2              5243
> test9+mypatch         5192 <-- a little bit worse
> test10-pre5+P1        5187
> test1                 3702 <-- no good scalability
> test10-pre5           2255 <-- negative scalability
> test9                 2193


We also did durability test of 2.4.0-test10-pre5.  Unfortunately
enough, we didn't successfully complete the test of Apache w/o
serialization (-DSINGLE_LISTEN_UNSERIALIZED_ACCEPT), it couldn't
continue to run for a night.  The kernel got complete deadlock.

The message is:
"Unable to handle kernel NULL pointer dereference NMI watchdog detected LOCKUP on 
CPU1."

Yes, obviously it's not Andrew's problem, that is genuine test10-pre5.

Hidden bugs are awakened by removing serialization.

If the bug is same as what I observed, It is NULL pointer dereference
on run-queue list.
--
Computer Systems Laboratory, Fujitsu Labs.
[EMAIL PROTECTED]
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