| 1 |
P.V.Anthony, mused, then expounded: |
| 2 |
> Hi, |
| 3 |
> |
| 4 |
> Need some more advice. |
| 5 |
> |
| 6 |
> Now the question is, is it better to go with 2 core or 4 core? |
| 7 |
> |
| 8 |
> The reason for this question is, that I heard there is a diminishing |
| 9 |
> return with more cores. Not sure if this is true with kernel 2.6.21 and |
| 10 |
> running at 64bit. |
| 11 |
> |
| 12 |
|
| 13 |
As far as the kernel is concerned, there are no issues. I've run on |
| 14 |
a 1024 shared memory ccNUMA system and regularly started up and killed |
| 15 |
1024 jobs withiout problems. |
| 16 |
|
| 17 |
> The server needed to built is for the following apps. |
| 18 |
> |
| 19 |
> Hardware. |
| 20 |
> 1. Tyan Tank GT20 (B5191) |
| 21 |
> 2. 2 x Sata drives |
| 22 |
> 3. Software raid 1 |
| 23 |
> 4. 4Gb ram ecc |
| 24 |
> 5. Intel Core2Duo E6420 or Intel Core2Quad E6600 |
| 25 |
> |
| 26 |
|
| 27 |
The Intel platform does not scale all that well. Plus it has |
| 28 |
limited I/O abilities. You will find a lot of issues with |
| 29 |
high i/o bandwidth simultanous applications. |
| 30 |
|
| 31 |
That said, it compiles like a screaming banshee. We currenly |
| 32 |
run ongoing testing on a small cluster of something like the |
| 33 |
above - 16 blades with quad core cpus (128P), running diskless |
| 34 |
over dual Infiniband links to lead and login nodes, dual core |
| 35 |
1U boxes with hardware raid. |
| 36 |
|
| 37 |
> Apps. |
| 38 |
> 1. Gentoo linux 64bit |
| 39 |
> 2. Apache 2 |
| 40 |
> 3. MySql |
| 41 |
> 4. Postgres |
| 42 |
> 5. Qmail |
| 43 |
> 6. Pure-ftpd |
| 44 |
> 7. Mod_perl |
| 45 |
> 8. php |
| 46 |
> 9. ruby |
| 47 |
> |
| 48 |
> Will all the instances of the apps be shared among the cores? |
| 49 |
> |
| 50 |
|
| 51 |
Good question. Without something like cpu sets, the sharing won't |
| 52 |
be equal amoung all cpus. |
| 53 |
|
| 54 |
> Please share the comments. |
| 55 |
> |
| 56 |
> I would really like to save some money. If the 2 core can do the job |
| 57 |
> there is quite a bit of savings buying just the 2 core. |
| 58 |
> |
| 59 |
|
| 60 |
Regardless of Intel platform, FSB saturaton will ocur due to the |
| 61 |
ancient bus. Additionally, unless you run 4-dimms, max memory |
| 62 |
bandwidth will not be achieved. Typically for the Intel 5000 |
| 63 |
chipset the motherboards have 8 DIMM slots. I see the one in the |
| 64 |
tank only has 6. Intel's northbridge came split the data up |
| 65 |
over 4 dimms to maximize bandwidth. It's important to performance. |
| 66 |
|
| 67 |
Additionally, there are other power savings issues to note - |
| 68 |
|
| 69 |
Woodcrest (dual core) does not support EIST (enhanced speed step) |
| 70 |
Clovertwon (quad core) does support EIST |
| 71 |
Memory should be run in performance mode. Allowing memory to |
| 72 |
be set into dynamic power mode (power savings) will decrease |
| 73 |
the max available bandwidth. |
| 74 |
Of the power saving software, powernowd allows better tuning and |
| 75 |
response to load changes. Much better than cpufreqd. |
| 76 |
|
| 77 |
|
| 78 |
|
| 79 |
> The other option is just to go with Pentium D with 2 core. That one is a |
| 80 |
> real saver. |
| 81 |
> |
| 82 |
|
| 83 |
And it's a crappy cpu. Don't waste you're money. Any AMD cpu running |
| 84 |
at half it's speed will eat it alive. |
| 85 |
|
| 86 |
Bob |
| 87 |
- |
| 88 |
-- |
| 89 |
gentoo-amd64@g.o mailing list |
Archives