On Fri, 2005-10-28 at 18:43 +0200, Martijn van Oosterhout wrote: > On Fri, Oct 28, 2005 at 05:05:25PM +0100, Simon Riggs wrote: > > 3. Helping Readahead efficiency: Currently blocks are allocated one at a > > time. If many tables are extending at the same time, the blocks from > > multiple tables will be intermixed together on the disk. Reading the > > data back takes more head movement and reduces the I/O rate. Allocating > > Ok, I agree with the rest but this isn't true. Any filesystem designed > in the last ten years leaves gaps around the place so when you extend a > file it remains consecutive. Some filesystems (like XFS) take it to > extremes). Interleaving blocks with this pattern hasn't been done since > FAT. > > That isn't to say that preextending isn't a good idea. With my pread() > patch it was the one use of lseek() I couldn't remove. > > Other than that, good thought...
Thanks. I wasn't aware of that. Best Regards, Simon Riggs ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly