lkml.org 
[lkml]   [1999]   [Dec]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] 2.3.34/pre-2.3.35-3 ramdisk/initrd NOT as a
In <Pine.SV4.3.96.991228110656.3710A-100000@scofolks.ocston.org> Tigran Aivazian (tigran@ocston.org) wrote:
TA> On Tue, 28 Dec 1999, Khimenko Victor wrote:
>> WHY seems it unacceptable to you ? That's the qyestion :-)

TA> I think I said that it is obviously unacceptable

"obviously unacceptable" is not an explanation :-)

TA> but I don't mind to repeat the obvious things.

Obvious ? Not to me at least :-)

TA> Namely, the amount of RAM in a node is a phenomenological constant the
TA> exact value of which should be irrelevant in non-failing cases.

Hmm. Why ?

TA> Of course, most sysadmins would have a rough idea on how much memory their
TA> nodes have but they don't *have* to.

There are enough utilities to find such infomation.

TA> A human being should just be able to tell the system "make me a ramdisk of
TA> size 64M with ext2 filesystem on it".

And system will try it's best to satisfy such request. You can ask system
to create 10GiB filesystem on 1GiB HDD (with FAT you can do such thing
easily :-) and you'll get random oopses later as well. Why it's Ok for
"normal" device and not Ok for ramdisk ?

TA> If it succeeds then the human has the right to expect it to work.

If there are no 64MiB of physical RAM then it cann't work. If you created
10GiB filesystem on 1GiB hdd -- you made something wrong, not OS. If you
created 64MiB ramdisk on system with 48MiB RAM you are done basically the
same mistake. What's the difference ?

TA> If it fails, *then* and only then he can ask (especially if its ENOMEM)
TA> "why did it fail?" and the answer which then turns phenomenological
TA> feature into pragmatical reality is "because you don't have enough
TA> physical RAM".

1) You can ignore amount of RAM ONLY since there are virtual memory. You
can not use virtual memory for ramdisk (not yet, at least :-) or for kernel
itself (including various drivers -- some will need big buffers). So here you
should be more carefull.
2) It does not the case with normal memory allocation in Linux. Why Ramdisk
should be different ?

TA> That is how UNIX systems work and that is how therefore Linux system
TA> should work.

Linux is NOT UNIX. Linux is dubbing Unix only where it's reasonable.

TA> But, as I don't know yet how to fix it, arguing further about it is rather
TA> silly on my side - I am trying to learn enough to fix it.

So far I can not understood why it should be fixed. At least I can not
understood why "normal OOM" (in case of OOM linux goes REALLY wild and will
kill random processes including syslog (almost always) and init (sometimes)
and this problem is there for years) does not bother you more then randisk
overflow case. To me situation where system can be killed with stupid runaway
process with memory leak or wild fork is MUCH worse then situation where you
created ramdisk more then there are physical RAM and then system was locked...
At least in second case you made something STUPID from ROOT...




-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:55    [W:0.057 / U:0.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site