[lkml]   [2004]   [Dec]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Subjectcifs large write performance improvements to Samba
    Some informal results evaluating the results of new cifs directio mount
    option and effects of changing the SMB network buffer size. All tests
    were run at least four times on each configuration and averaged.

    Command executed: time dd if=/dev/zero of=/mnt/ofile bs=1M count=400
    (400MB copy to server with large writes)

    MemTotal on system: 905148kB (from /proc/meminfo)

    Kernel: current 2.6.10-rc3 from bk
    SLES9 JFS (and EXT3 on one test). Intel Pentium M, relatively slower IDE
    drives (laptop). Kernel compiled for debug memory allocations.

    CIFS filesystem version: 1.28

    Samba version 3.0.10pre (current svn)

    mount over loopback interface to samba server on the same box (to
    maximize network transfer speed)

    CIFS mount (default): 1 minute 46 seconds (constrained largely by the 4K
    writes, due to no implementation of page coalescing and no
    implementation of cifs_writepages)

    CIFS mount (directio): 35.9 seconds (huge improvement due to now being
    able to do up to 16K size writes to server, and reducing double caching
    effects since page cache not used on client side). Running with a faster
    processor (otherwise the same) this dropped to 20.8 second average.

    CIFS mount (directio, insmod specifying larger CIFSMaxBufSize of 65024):
    24.0 seconds The larger buffer size (almost 4 times larger) led to
    significant improvements (going beyond this to 120K network write size
    did not improve performance on this test, actually got a bit worse).
    Running with a faster processor (otherwise the same) this improved to
    19.3 seconds average (and using the even larger 120K write size
    performance dropped slightly to 20.6 seconds)

    Additional comparison points -
    The older smbfs filesystem: 1 minute 7.04 seconds (note that smbfs read
    performance is much worse than cifs in part due to lack of readpages
    implementation in smbfs, but the writepage performances differ less

    Local performance:
    JFS 3.5 seconds
    EXT3 12.8 seconds

    EXT3 was somewhat slower than I expected.

    The does show that cifs directio mounts help a lot for large file copy -
    and also that cifs badly needs an asyn writepages implementation (which
    has obviously helped NFS on this kind of test). In addition CIFS needs
    to reduce some of the CPU (one of the large buf allocs and memcpys in
    the write path can be eliminated with some reasonably obvious changes).
    I doubt that enough analysis on the Samba server side has been done for
    this particular case on 2.6 and that might yield some easy improvements
    as well. Also note that there was one case in which cifs to Samba ran
    into the expected memory contention deadlock (client writes dirty page
    to server, server blocked on memory allocation which is blocked on
    client's write).

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 14:08    [W:3.454 / U:0.064 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site