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SubjectRe: Scalability requirements for sysv ipc
Manfred Spraul wrote:
> Nadia Derbey wrote:
>
>> Manfred Spraul wrote:
>>
>>>
>>> A microbenchmark on a single-cpu system doesn't help much (except
>>> that 2.6.25 is around factor 2 slower for sysv msg ping-pong between
>>> two tasks compared to the numbers I remember from older kernels....)
>>>
>>
>> If I remember well, at that time I had used ctxbench and I wrote some
>> other small scripts.
>> And the results I had were around 2 or 3% slowdown, but I have to
>> confirm that by checking in my archives.
>>
> Do you have access to multi-core systems? The "best case" for the rcu
> code would be
> - 8 or 16 cores
> - one instance of ctxbench running on each core, bound to that core.
>
> I'd expect a significant slowdown. The big question is if it matters.
>
> --
> Manfred
>
>

Hi,

Here is what I could find on my side:

=============================================================

lkernel@akt$ cat tst3/res_new/output
[root@akt tests]# echo 32768 > /proc/sys/kernel/msgmni
[root@akt tests]# ./msgbench_std_dev_plot -n
32768000 msgget iterations in 21.469724 seconds = 1526294/sec

32768000 msgsnd iterations in 18.891328 seconds = 1734583/sec

32768000 msgctl(ipc_stat) iterations in 15.359802 seconds = 2133472/sec

32768000 msgctl(msg_stat) iterations in 15.296114 seconds = 2142260/sec

32768000 msgctl(ipc_rmid) iterations in 32.981277 seconds = 993542/sec

AVERAGE STD_DEV MIN MAX
GET: 21469.724000 566.024657 19880 23607
SEND: 18891.328000 515.542311 18433 21962
IPC_STAT: 15359.802000 274.918673 15147 17166
MSG_STAT: 15296.114000 155.775508 15138 16790
RM: 32981.277000 675.621060 32141 35433


lkernel@akt$ cat tst3/res_ref/output
[root@akt tests]# echo 32768 > /proc/sys/kernel/msgmni
[root@akt tests]# ./msgbench_std_dev_plot -r
32768000 msgget iterations in 665.842852 seconds = 49213/sec

32768000 msgsnd iterations in 18.363853 seconds = 1784458/sec

32768000 msgctl(ipc_stat) iterations in 14.609669 seconds = 2243001/sec

32768000 msgctl(msg_stat) iterations in 14.774829 seconds = 2217950/sec

32768000 msgctl(ipc_rmid) iterations in 31.134984 seconds = 1052483/sec

AVERAGE STD_DEV MIN MAX
GET: 665842.852000 946.697555 654049 672208
SEND: 18363.853000 107.514954 18295 19563
IPC_STAT: 14609.669000 43.100272 14529 14881
MSG_STAT: 14774.829000 97.174924 14516 15436
RM: 31134.984000 444.612055 30521 33523


==================================================================

Unfortunately, I haven't kept the exact kernel release numbers, but the
testing method was:
res_ref = unpatched kernel
res_new = same kernel release with my patches applied.

What I'll try to do is to re-run your tests (pmsg and psem) with this
method (from my what I saw, the patches applied on a 2.6.23-rc4-mm1),
but I can't do it before Thursday.

Regards,
Nadia


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