On Thu, 10 May 2007 11:34:46 +0100 Neil Bothwick <[EMAIL PROTECTED]> wrote:
> On Thu, 10 May 2007 12:11:34 +0200, Benno Schulenberg wrote: > > > > No idea, but I tried it when I encountered that page and portage > > > operations were measurably faster. > > > > That might well be just the transfer effect: you went from an old > > fragmented file system to a fresh unfragmented one. > > I allowed for that. I created a new filesystem for /usr/portage - I > had been using a directory in /usr before. > > Well, maybe it has to do with the efficiency of reading discontiguous blocks from one file as opposed to a filesystem. Since it's a sparse file, there might be a lot of 'space' that, if it were on an actual disk, the heads would have to pass over; thus there may be a way in which a sparse file is more efficient than a regular filesystem. Remeber that the files in portage are, except for distfiles, quite small. By my calculation, the average size for files and directories under $PORTDIR (excluding $DISTDIR of course) is only 62 bytes. What would you bet that on a disk partition, the other 962 to 4034 bytes per block (I couldn't have block sizes less than 1K on reiser for my portage, and 4096 is the default for most FS's) are filled with nothing, and the heads need to pass over them to read the next block. On a sparse file that space is merely reserved, it needn't actually exist. Hope that helps you conceptualize the difference. -- [EMAIL PROTECTED] mailing list
