Messages in this thread | | | Date | Thu, 02 Nov 2006 23:32:11 +0100 | From | Gabriel C <> | Subject | Re: New filesystem for Linux |
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Mikulas Patocka wrote: > Hi >
Hi
> As my PhD thesis, I am designing and writing a filesystem, and it's now in > a state that it can be released. You can download it from > http://artax.karlin.mff.cuni.cz/~mikulas/spadfs/ >
Does not compile for me , using 2.6.18.1 , gcc 4.1.1. Here the error :
/work/crazy/packages/fs/spadfs-0.9.0/super.c: In function 'SPADFS_GET_SB': /work/crazy/packages/fs/spadfs-0.9.0/super.c:636: error: too few arguments to function 'get_sb_bdev' /work/crazy/packages/fs/spadfs-0.9.0/super.c: At top level: /work/crazy/packages/fs/spadfs-0.9.0/super.c:645: warning: initialization from incompatible pointer type /work/crazy/packages/fs/spadfs-0.9.0/super.c:651: warning: initialization from incompatible pointer type /work/crazy/packages/fs/spadfs-0.9.0/super.c: In function 'SPADFS_GET_SB': /work/crazy/packages/fs/spadfs-0.9.0/super.c:637: warning: control reaches end of non-void function make[2]: *** [/work/crazy/packages/fs/spadfs-0.9.0/super.o] Error 1 make[1]: *** [_module_/work/crazy/packages/fs/spadfs-0.9.0] Error 2 make[1]: Leaving directory `/usr/src/linux-2.6.18-fw2' make: *** [spadfs] Error 2
> It has some new features, such as keeping inode information directly in > directory (until you create hardlink) so that ls -la doesn't seek much, > new method to keep data consistent in case of crashes (instead of > journaling), free space is organized in lists of free runs and converted > to bitmap only in case of extreme fragmentation. > > It is not very widely tested, so if you want, test it. > > I have these questions: > > * There is a rw semaphore that is locked for read for nearly all > operations and locked for write only rarely. However locking for read > causes cache line pingpong on SMP systems. Do you have an idea how to make > it better? > > It could be improved by making a semaphore for each CPU and locking for > read only the CPU's semaphore and for write all semaphores. Or is there a > better method? > > * This leads to another observation --- on i386 locking a semaphore is 2 > instructions, on x86_64 it is a call to two nested functions. Has it some > reason or was it just implementator's laziness? Given the fact that locked > instruction takes 16 ticks on Opteron (and can overlap about 2 ticks with > other instructions), it would make sense to have optimized semaphores too. > > * How to implement ordered-data consistency? That would mean that on > internal sync event, I'd have to flush all pages of a files that were > extended. I could scan all dirty inodes and find pages to flush --- what > kernel function would you recommend for doing it? Currently I call only > sync_blockdev which doesn't touch buffers attached to pages. > > Mikulas > - >
Gabriel
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