samba - Sep 2025 - How to speed up small file writes? (WSL2 / Windows)

On Wed, Sep 10, 2025 at 9:49?PM Michael Tokarev <mjt at tls.msk.ru>
wrote:
> Please also do another test: windows to a network drive which
> is run by another windows machine (I dunno if you can do this on
> a single machine though).
That?s a great suggestion! It would be possible to test
Windows-to-Windows SMB performance with a Windows VM, but I am too lazy
to set that up right now. What I did, however, is test extraction speed
with the tar file hosted on Windows from Linux:

    root at felix-x1t3-11:/tmp/test# time tar xfz 2025-09-10+08_test.tgz

    real    0m38.990s
    user    0m3.082s
    sys     0m3.037s

I also tried a few more tweaks to the Samba configuration by removing
meta data preservation, see below. With that I can get down to 135
seconds:

    PS Microsoft.PowerShell.Core\FileSystem::\\172.18.61.229\share\test>
    Measure-Command {
    >> tar xfz .\2025-09-10+08_test.tgz
    >> }


    Days              : 0
    Hours             : 0
    Minutes           : 2
    Seconds           : 15
    Milliseconds      : 199
    Ticks             : 1351991956
    TotalDays         : 0.00156480550462963
    TotalHours        : 0.0375553321111111
    TotalMinutes      : 2.25331992666667
    TotalSeconds      : 135.1991956
    TotalMilliseconds : 135199.1956

That?s still 3.5 times slower than in the other direction:

At least for small file writes, the SMB server built into Windows seems
to be considerably faster than Samba!

Next I want to try KSMBD. The goal is to get maximum small file write
speed. No file meta data needs to be preserved.

My current `/etc/samba/smb.conf`:

    [global]
       workgroup = WORKGROUP
       security  = user
       map to guest = Bad User
       load printers = no
       disable spoolss = yes
       strict locking = no
       use sendfile = yes
       min receivefile size = 128k
       socket options = IPTOS_LOWDELAY TCP_NODELAY
       oplocks = yes
       aio read size = 1
       aio write size = 1
       kernel oplocks = no
       host msdfs = no
       strict sync = no
       smb encrypt = disabled

       ea support = no
       store dos attributes = no
       map archive = no
       nt acl support = no

       durable handles = no
       posix locking = no

    [share]
       path = /home/felix/tmp
       read only = no
       browseable = yes
       force user = felix
       create mask = 0644
       directory mask = 0755

The big question still is: Can it be made faster?

Find some more tests below, now with the following setup:

  * SMB Guest: Windows 11 Pro x64

  * SMB Host: Hyper-V/Arch Linux inside the above Windows, connected via
    an internal Hyper-V bridge

Samba 4.22.4:

  * `/etc/samba/smb.conf`:

        [global]
                load printers = no
                disable spoolss = yes
                strict locking = no
                use sendfile = yes
                min receivefile size = 128k
                socket options = IPTOS_LOWDELAY TCP_NODELAY
                oplocks = yes
                aio read size = 1
                aio write size = 1
                kernel oplocks = no
                host msdfs = no
                strict sync = no
                client smb encrypt = off

        [share]
                path = /home/felix/tmp
                read only = no
                store dos attributes = no

  * I mounted the share and extracted the test data (see initial post):

        PS C:\> net use Z: \\10.149.217.2\share /user:felix *
        PS C:\> z:
        PS Z:\> Measure-Command { tar xfz 2025-09-10+08_test.tgz }


        Days              : 0
        Hours             : 0
        Minutes           : 1
        Seconds           : 28
        Milliseconds      : 789
        Ticks             : 887896536
        TotalDays         : 0.00102765802777778
        TotalHours        : 0.0246637926666667
        TotalMinutes      : 1.47982756
        TotalSeconds      : 88.7896536
        TotalMilliseconds : 88789.6536

KSMBD with (dangerous) multi channel is just 23% faster:

  * `/etc/ksmbd/ksmbd.conf`:

        [global]
                server multi channel support = yes
                smb3 encryption = disabled

        [share]
                path = /home/felix/tmp
                read only = no
                hide dot files = no
                store dos attributes = no

  * Extraction takes 72 seconds:

        PS Z:\> Measure-Command { tar xfz 2025-09-10+08_test.tgz }


        Days              : 0
        Hours             : 0
        Minutes           : 1
        Seconds           : 12
        Milliseconds      : 5
        Ticks             : 720059246
        TotalDays         : 0.000833401905092593
        TotalHours        : 0.0200016457222222
        TotalMinutes      : 1.20009874333333
        TotalSeconds      : 72.0059246
        TotalMilliseconds : 72005.9246

Extracting the archive on Linux is 25 times faster than KSMBD:

    $ time tar xfz 2025-09-10+08_test.tgz

    real    0m2.931s
    user    0m2.292s
    sys     0m1.220s