On Thursday 07 July 2005 02:45, Hans Reiser wrote: > Jeff, are you sure that you need this code to exist? Here are the > problems I see: > > for the average case, it is suboptimal. The seeks to the bitmaps > are far more expensive than the averaged cost of keeping them in ram.
It would be good to see the benchmark results which your opinion is based on. I know that on-demand bitmap loading in reiser4 was under suspicion several times but I don't remember any benchmark results which showed a slowdown regarding that. > > for 16TB filesystems, they will have plenty of budget for ram > > it complicates code if it has to worry about such things as not > enough clean memory for holding bitmaps, etc. > > It is more appropriate to write this kind of code for the > development branch which is V4. This kind of code is likely to have > hard to test and hit bugs. > Lena, may you check how the bitmap on-demand loading patch affects, say, mongo results for reiserfs? Thanks, Alex.
