Messages in this thread | | | Date | Fri, 6 Sep 2002 18:24:57 +0100 | From | "Stephen C. Tweedie" <> | Subject | Re: ext3 throughput woes on certain (possibly heavily fragmented) files |
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Hi,
On Fri, Sep 06, 2002 at 09:14:28PM +0400, Nikita Danilov wrote:
> Another possible solution is to try to "defer" allocation. For example, > in reiser4 (and XFS, I believe) extents are allocated on the transaction > commit and as a result, if file was created by several writes, it will > still be allocated as one extent.
Ext2 has a preallocation mechanism so that if you have multiple writes, they get dealt with to some extent as a single allocation. However, that doesn't work over close(): the preallocated blocks are discarded wheneven we close the file.
The problem with mail files, though, is that they tend to grow quite slowly, so the writes span very many transactions and we don't have that opportunity for coalescing the writes. Actively defragmenting on writes is an alternative in that case.
Cheers, Stephen - 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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