Re: e2fslibs for ext2fs?

[Ognyan Kulev]

Marcus Brinkmann wrote:
> Note that I mentioned io_map and that its implementation will not be helped
> at all by such a simple library.  That includes large file support.  Large
> filesystems might trivially be supported by such a library if it always
> accesses the store directly, without any mapping.  No mapping however means
> no cache, and that's where your performance is saying good bye.

In addition, all these library functions are layered upon a block layer 
inefficiently.  The block layer has a very small cache (8 blocks).  You 
can increase block count, but the cache algorithm is optimized for small 
cache and will definately be very inefficient for larger caches.  The 
library functions that need to use part of a block don't get pointer to 
the already cached block, but supply own buffer where the block layer 
will copy bytes from its cache.  This means that there are _a lot_ of 
redundant memory copies.

This doesn't mean the library is bad.  It's just optimized for e2fsck 
and other offline programs, like e2tools.

Regards
--
Ognyan Kulev <ogi@{fmi.uni-sofia.bg,fsa-bg.org}>
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