Messages in this thread | | | Date | Wed, 30 Oct 2002 12:26:07 -0600 | From | Lee Leahu <> | Subject | Re: The reason to call it 3.0 is the desktop (was Re: [OT] 2.6 not 3.0 - (NUMA)) |
| |
Pardon my ignorance,
How does Readahead relate to journaling filesystems such as ReiserFS, or XFS?
Do they have the same or similar problems that I've been reading about with ext2/3?
Andrew Morton <akpm@digeo.com> scribbled something about Re: The reason to call it 3.0 is the desktop (was Re: [OT] 2.6 not 3.0 - (NUMA)):
> Daniel Phillips wrote: > > > > On Sunday 06 October 2002 17:19, Martin J. Bligh wrote: > > > > Then there's the issue of application startup. There's not enough > > > > read ahead. This is especially sad, as the order of page faults is > > > > at least partially predictable. > > > > > > Is the problem really, fundamentally a lack of readahead in the > > > kernel? Or is it that your application is huge bloated pig? > > > > Readahead isn't the only problem, but it is a huge problem. The current > > readahead model is per-inode, which is very little help with lots of small > > files, especially if they are fragmented or out of order. There are various > > ways to fix this; they are all difficult[1]. Fortunately, we can call this > > "tuning work" so it can be done during the stable series. > > > > [1] We could teach each filesystem how to read ahead across directories, or > > we could teach the vfs how to do physical readahead. Choose your poison. > > Devices do physical readahead, and it works nicely. > > Go into ext2_new_inode, replace the call to find_group_dir with > find_group_other. Then untar a kernel tree, unmount the fs, > remount it and see how long it takes to do a > > `find . -type f xargs cat > /dev/null' > > on that tree. If your disk is like my disk, you will achieve > full disk bandwidth. > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
-- +----------------------------------+---------------------------------+ | Lee Leahu | voice -> 708-444-2690 | | Internet Technology Specialist | fax -> 708-444-2697 | | RICIS, Inc. | email -> lee@ricis.com | +----------------------------------+---------------------------------+ | I cannot conceive that anybody will require multiplications at the | | rate of 40,000 or even 4,000 per hour ... | | -- F. H. Wales (1936) | +--------------------------------------------------------------------+ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |