1 |
On Sat, 31 Jul 2004 09:57:47 -0600, Gyujin Park <gpark@××××××.com> wrote: |
2 |
> Thanks. Yes, I will definitely go for a search on this on other lists too. |
3 |
> |
4 |
> The command line you gave me actually made my memory free. It's kind of |
5 |
> interesting. You said it would freeze, but it actually cleared my memory. |
6 |
> |
7 |
> So I did |
8 |
> dd if=/dev/hda1 of=/dev/null bs=400M |
9 |
> |
10 |
> and the result was |
11 |
> 0+1 records in |
12 |
> 0+1 records out |
13 |
> |
14 |
> and I did |
15 |
> free |
16 |
> and suddenly 116MB Free Memory space. :O |
17 |
> |
18 |
> total used free shared buffers cached |
19 |
> Mem: 514688 397888 116800 0 11132 251636 |
20 |
> -/+ buffers/cache: 135120 379568 |
21 |
> Swap: 2008116 0 2008116 |
22 |
|
23 |
It didn't freeze or turn to swap (which has still not been disproven |
24 |
to work) probably because 400MB is coincidentally the amount of memory |
25 |
you *can* allocate without, in addition to your running programs, |
26 |
cross 512MB. You probably flushed the cache-and-buffers down to 25 |
27 |
megs as your other 'free' output displayed. |
28 |
|
29 |
If you ran free earlier than you just did, you probably would have |
30 |
seen a lot more on the figure as free - but again, the realistical |
31 |
figure is now 379568, which as you may noticed has changed very little |
32 |
from your earlier outputs. |
33 |
The memory used by your programs alone is around 514M-379M = 135M in |
34 |
that output. The rest is either in cache and buffers, or NOT in cache |
35 |
and buffers right after you did a dd. |
36 |
|
37 |
> Yes, I know system goes slow when it runs into swap since HDD aren't that fast |
38 |
> enough re-write speed as Memory. |
39 |
You want to avoid it. Always. It loads your entire system and bugs its |
40 |
speed down to a fraction of its possibly throughput. |
41 |
|
42 |
> I agree, systems in both linux and windows aren't very optimized at using SWAP. |
43 |
> Macs have problems also. Although, the big problem is *not turning into swap!!* |
44 |
> |
45 |
> May be this is an issue with 2004.2 Stage 3 installation. I am currently using |
46 |
> Gentoo 2004.0 (since 2004.1 had pour support for eth0 cards.) for my desktop, and |
47 |
> it runs into swap fine. |
48 |
|
49 |
Like I said, I have seen no evidence to suggest swap isn't working as |
50 |
it should. Your memory requirements - when you consider the real |
51 |
meanings of free-at-all and free-not-counting-cache-and-buffers, and |
52 |
the flexibility of said cache, it seems to me you never actually made |
53 |
your comptuer use all your memory, and then it becomes a very good |
54 |
thing that it doesn't turn to swap. |
55 |
|
56 |
Actually, it might have swapped a little after the dd with a 400mb |
57 |
allocation, but decided to swap right back in when it saw memory was |
58 |
free. Possibly the fact you're allocating 400mb on a system that has |
59 |
380MB free not counting cache doesn't make it swap; maybe memory is |
60 |
more flexible with a relatively small figure like 20mb than I thought. |
61 |
|
62 |
A sure yet dangerous test, as I suggested, is to use dd with a figure |
63 |
larger than yor physical memory or possibly free memory- 500 would be |
64 |
fine; a runnins system needs more than the 12mb that leaves for it. |
65 |
600 would be a sure test, but again - *if* it swaps it'll become slow, |
66 |
if it doesn't it'll probably crash, elegantly or not. |
67 |
|
68 |
|
69 |
|
70 |
But basically, I think you have none of the problems you thougt you had. |
71 |
|
72 |
--Bart |
73 |
|
74 |
-- |
75 |
gentoo-performance@g.o mailing list |