Hi!
> It has long been an architectural weakness of ReiserFS that we allocate block
> numbers to buffers as we need each buffer. We knew that we should cure this by
> doing either pre-allocation of blocknrs as ext2 does (meaning allocate many
> blocks at a time, and then keep them reserved for that file until file close),
> or allocating block numbers on dirty buffer/page flush as XFS does. It is for
> sure the case that our current practice of allocating blocks as we need new
> buffers to write into is a bad architecture. Yura wrote some pre-allocation code
> that improved our performance by as much as 4x in some benchmarks, but I
> discouraged it because I prefer allocate on flush. This decision is hurting us
> at the moment. Pre-allocation is much easier to code (and already written by
> Yura for an older version), allocate on flush is the right answer long-term.
> Zam has been working on allocate on flush for about 6 weeks, but it is not ready
> yet. I think we will have Yura throw in his pre-allocation code
Does on-disk layout differ between no-prealloc, prealloc, and
alloc-on-flush versions? Probably not. Then there's no problem getting
no-prealloc into kernel first ASAP, then changing it to
alloc-on-flush.
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- 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/
This archive was generated by hypermail 2b29 : Wed Mar 15 2000 - 21:00:26 EST