Re: kernels and b0xen
On 23 Jan, this message from simon@nuit.ca echoed through cyberspace:
> On Wed, Jan 22, 2003 at 22:26:00 +0100, Michel Lanners composed:
>> On 22 Jan, this message from simon@nuit.ca echoed through cyberspace:
>>
>> >> - check your hard disk speed: hdparm -tT /dev/<disk with kernel source>
>> >> (is non-destructive; post the result to compare)
>> >
>> > 1. Timing buffer-cache reads: 128 MB in 3.73 seconds = 34.32 MB/sec
>> > Timing buffered disk reads: 64 MB in 18.10 seconds = 3.54 MB/sec
>> >
>> > 2. /dev/sda:
>> > Timing buffer-cache reads: 128 MB in 3.68 seconds = 34.78 MB/sec
>> > Timing buffered disk reads: 64 MB in 12.71 seconds = 5.04 MB/sec
>>
>> 34 MB/sec for buffered reads s essentially a measure of memory
>> bandwidth. And 34 MB/sec seems low for a 7500-class machine. I get 45
>> MB/sec (OK, on an interleaved memory config).
>
> that may be because of the smallish amount of RAM on this thing;
> interleaved i was getting pretty much the same ratings.
Yes, non-interleaved can make that difference.
> it may have to
> do with the RAM sticks' actual ms speed rating - i have 4MB sticks @ 70
> ms IIRC, and some 8MB sticks @ 60 ms.
No, the box will drive the memory chips the same independent of what
speed rating you put in. These things don't have EEPROMs with config
data, unlike modern SDRAMs.
The only advantage you may get from faster memory is faster memory bus
in interleaved configs, where we seem to hit some hardware limitation.
>> On my IDE disk in the 7600, connected to a Promise IDE controller, I get
>> 12 MB/sec. That _does_ help a lot for kernel compiles.
>
> i'm sure that would help serving web pages too. maybe i can improve
> things just with a SCSI card installed, and some extra RAM (in time).
Well, personally, I would probably not invest in a SCSI controller. IDE
disks and controllers are dirt cheap for very decent performance,
whereas even an oldish fast-wide SCSI controller is still expensive.
That is, unless you buy on Ebay :-)
Cheers
Michel
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