Since the performance improvements seen so far are quite encouraging, and momentum is picking up so well, I started looking through the patches from Alex ... just a quick code walkthrough to get a hang of it and think about what kind of simplifications might be possible and what it might take for inclusion.
I haven't had a chance to go too deep line by line yet, but thought I'd initiate some discussion with some first impressions and summary of what directions I hear several people converging towards to validate if I'm on the right track here. diffstat of the 3 patches : 22 files changed, 5920 insertions(+), 47 deletions. The largest is in the extents patch (2743), mballoc is 1968, and delalloc is 1209. To use delalloc, which gives us all the performance benefits, right now we need all the 3 patches to be used in conjunction. Supporting extent map btrees as well as traditional indexing and associated options for compatibility etc is perhaps the more invasive of changes. Given that keeping ext3 stable and maintainable is a key concern (that is after all a major reason why a lot of users rely on ext3), a somewhat incremental approach is desirable. So, I'll start from the direction that has been suggested by some -- (1) delayed allocation without changing the on-disk format. And then later (2) go on to breaking format with all changes for scalability to larger files with full extents support (haven't thought enough about this yet - maybe in a separate mail) A few random things that come to mind for (1), going through the code: - There might be possibilities for code reduction, by extending generic routines as far as possible, e.g. ext3_wb_writepages has a lot in common with generic writepages. That would also make it easier to maintain. - Similarly, how about (as Mingming I think already hinted) implementing ext3_get_blocks to do multi-block lookup and allocation and using it in delalloc ? Hmm, maybe I speak too soon - have to look at the interfaces more closely and verify if this is feasible. Regards Suparna -- Suparna Bhattacharya ([EMAIL PROTECTED]) Linux Technology Center IBM Software Lab, India - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
