Status and demo of SMB3 Multi-Channel in Samba

Linda W samba at
Wed Oct 29 23:52:20 MDT 2014

Jeremy Allison wrote:
> Did you set the "aio read size" or "aio write size" parameters
> in your smb.conf ?
> That allows smbd to use a thread per outstanding read or write
> request which should use multiple cores, depending on how hard
> the client is driving the server.
> Jeremy.
Didn't notice an appreciable difference nor an extra thread (monitoring with
htop to show user threads -- which are hilighted.

Tried with:
    aio read size = 65536
    aio write size = 65536
(as I was using a 16M io/size, I didn't try other aio sizes).

Tried with those on the test shares, as well
as stacking on "vfs_aio_thread" at the end of the vfs chain --
neither seemed to spawn off extra threads -- both had the
smb process in the mid 90% usage range for 1 core.

If I had a hint of multiple threads, confining them to the same
phys CPU (2-socket NUMA-aware kernel), but even putting
all the dev interrupts on the same cpu as the program gave
no appreciable boost**.

A single run can vary from 450-650 reads and
350-580 writes (at least right now).  have had other days
when they were less variable (500's + 400's respectively

(units in mbps).

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