Re: /tmp as tmpfs and consequence for imaging software

[Goswin von Brederlow <goswin-v-b@web.de>]

Chow Loong Jin <hyperair@ubuntu.com> writes:

> On 16/11/2011 22:45, Salvo Tomaselli wrote:
>> 
>>> Given that any burning software can (approximately) determine what size the
>>> ISO file will be, it should really not start to write it in /tmp when the
>>> /tmp size is not big enough (which the software can also check). Prompting
>>> a user with "I will not be able to write ${file} in /tmp, please point me
>>> to a location where I can." should not be too much of a problem.
>> 
>> Yes it can (and does) if there is not enough space in /tmp. What mostly scares 
>> me is the idea of paging out 4GiB to the swap partition (assuming it is so 
>> big), because of a tmpfs configured to be very large.
>
> Doesn't tmpfs default to 50% of your memory? Unless you have 8GB of memory, you
> shouldn't be seeing 4GB worth of data getting into /tmp by mistake.

4GiB at 100MiB/s = 40s.

So the following code could block for a short while:

char *mem = malloc(4*1024*1024*1024);
memset(mem, 0, 4*1024*1024*1024);

So if you do use a lot of /tmp and have code that eats that much memory
at once then you might want to change your config from the default.

But seriously, how common is that?

MfG
        Goswin