[Samba] Samba write performance in kernel

Lin Mac mkl23 at hotmail.com
Tue Aug 26 09:41:51 GMT 2008


I would like to know is it possible to make writing file to samba completely in kernel?

I'm using a slow CPU (FA526) , and the memory copy is even slower. The reading performance is over 7 MB/s, with mmap and sendfile enabled, while writing is only 4-5 MB/s. Without mmap and sendfile, reading from samba is also about 4-5 MB/s. I use Oprofile to profile writing file to samba and found that CPU takes over 30% CPU time on copy_from/to_user, so I think going to user space and back again is the bottleneck.

Since there is sendfile, why is'nt there counterpart on write path? Is there some difficalties or what? Is it implementable?

Please give me some advice.

Best Regards,
Mac Lin

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