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Hi, On Sat, Oct 08, 2005 at 01:59:48AM -0400, Lee Revell wrote: > On Sat, 2005-10-08 at 00:39 -0400, Xin Zhao wrote: > > I noticed that when doing large file copy or linux kernel compilation > > in a NFS direcotry, the performance is not bad compared to local disk > > filesystem such as ext2. However, if I do linux kernel tarball > > decompression on a NFS directory, the performance is much worse than > > local disk filesystem (over 3 times slower). Anybody know the reason? > > Because NFS requires all writes to be synchronous by default, and > uncompressing the kernel is the most write intensive of those three > operations. Mount with the async option and the performance should be > closer to a local disk. Obviously this is more dangerous. I don't agree with you, Lee. My NFS is mounted with async by default, and what takes the most time when extracting a kernel archive is that tar does a stat() on every file before writing it. And THAT stat() prevents writes from being buffered. A better solution might be to process several files in parallel (multi-process/multi-thread). Perhaps a project for a new tar ? Just for a test, I tried extracting multiple files in parallel. The method is completely crappy, but I could saturate my NFS server this way : $ tar ztf /tmp/linux-2.6.9.tar.gz >/tmp/file-list $ sed -n '1~4p' < /tmp/file-list >/tmp/file-list1 $ sed -n '2~4p' < /tmp/file-list >/tmp/file-list2 $ sed -n '3~4p' < /tmp/file-list >/tmp/file-list3 $ sed -n '4~4p' < /tmp/file-list >/tmp/file-list4 $ tar zxf /tmp/linux-2.6.9.tar.gz -T /tmp/file-list1 & tar zxf /tmp/linux-2.6.9.tar.gz -T /tmp/file-list2 & tar zxf /tmp/linux-2.6.9.tar.gz -T /tmp/file-list3 & tar zxf /tmp/linux-2.6.9.tar.gz -T /tmp/file-list4 & wait OK, it finally took more time, although the server was saturated (maybe it crawled under seeks at the end, I did not check). This may constitute a starting point for people having more time to research in this area. > Lee Cheers, Willy - 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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