Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: Ext2 Directory Index - Delete Performance | Date | Thu, 19 Apr 2001 13:44:03 +0200 |
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> On Wed, 18 Apr 2001, Rik van Riel wrote: > > One thing we should do is make sure the buffer cache code sets > > the referenced bit on pages, so we don't recycle buffer cache > > pages early. > > > > This should leave more space for the buffercache and lead to us > > reclaiming the (now unused) space in the dentry cache instead... > > Sorry, but that's just plain wrong. We shouldn't keep inode table in > buffer-cache at all. And we should be more aggressive on icache - > dcache looks sane now (recent 2.4.4-pre), but icache holds unused > inodes for too long. And freeing them is very slow _and_ random - > recipe for kmem_cache fragmentation. > > /me sits down to port inode-table-in-pagecache to 2.4.4-pre4...
The Ext2 inode-table maps nicely to the page cache with the current page cache interface because it has uniform sized chunks that are accessed one at a time, and likewise for the group descriptor cache.
*But* the directory code in page cache with your current approach does not work out nicely with my directory index - it doesn't have page-sized chunks and access to them is overlapped. This isn't an isolated problem, it's a problem we've managed to avoid dealing with so far because much of the file code we have does satisfy your two pre-conditions:
- Data groups naturally into pages - Access to data items is strictly serial
We need a way of accessing the page cache that doesn't rely on either of those two assumptions. -- Daniel - 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/
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