Messages in this thread | | | Date | Tue, 21 Mar 2000 22:44:04 +0100 | From | Pavel Machek <> | Subject | Re: Memory Mapped Filesystem |
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Hi! > > I converted yesterday an Alpha station to ext3 (and it works great). > However, I kept /tmp as ext2 since the README distributed with ext3 says > that it would be more efficient this way. This is somehow inelegant, > since this means that there is still one fsck (which can fail). > > I could do an automatic mke2fs on the device, at boot time, since this > is /tmp. However, with automatic numbering of partitions, I feel a bit > unsafe with a mke2fs in a boot script. > > So I remembered that, under FreeBSD, I use mfs for /tmp: a filesystem > mapped in memory. This is not quite a ramdisk since: > -- it can be swapped out > -- it frees unsued pages when a file is removed > Somehow, this is like sharing space for /tmp and swap. I find this > scheme elegant and it would fit my needs. > > Therefore, I intend to implement such a filesystem. For this, I need > some help; specifically, I ask myself the following questions: > -- does such a filesystem already exists ?
I think so.
> -- would it be easier to modify the ramdisk to be able to be > swapped out, and stubs in one filesystem to unmap unused pages ? > -- how do I allocate memory from within the kernel, such that this > memory might be swapped out ? I can do a do_mmap(), but, from > my (rather low) understanding of the memory management in Linux, > this mapping would be specific to one process. I could run > a kernel thread (well, at least I believe I could) but I would > run into the "Minix-single-threaded-filesystem". > -- what happens if I create a file on such a filesystem and try to > swapon it ? > -- does all this make sense ? Is there a better solution ?
Are you sure /tmp is used so much it makes sense? Pavel -- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents me at discuss@linmodems.org
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