Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: The reason to call it 3.0 is the desktop (was Re: [OT] 2.6 not 3.0 - (NUMA)) | Date | Mon, 7 Oct 2002 22:22:51 +0200 |
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On Monday 07 October 2002 22:14, Andrew Morton wrote: > Daniel Phillips wrote: > > > > This is easy to verify: say you have 100 MB of kernel source stored in, say, > > 50 different clumps on disk. > > Disks use segmentation on their readahead buffers. Typically four-way. > So they will only buffer four different chunks of disk at a time. > > If you're reading from 50 different places on disk, the disk keeps > invalidating readahead at the segment level.
Sure, and kernel-based physical readahead would not have that problem. (Kernel-based physical readahead has its own problems, for example: how do you determine that a given physical block is already cached in an inode and so should be ignored as a readahead candidate?)
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