Subject: Re: [PATCH 0/4] [RFC] virtio-net: Improve small packet performance

From: "Michael S. Tsirkin" <[email-masked]>
Date: Thu, 5 May 2011 18:34:13 +0300

On Thu, May 05, 2011 at 08:57:13PM +0530, Krishna Kumar2 wrote:
> "Michael S. Tsirkin" <[email-masked]> wrote on 05/05/2011 02:34:39 PM:
> 
> > > Do I need to apply all the patches and simply test?
> > >
> > > Thanks,
> > >
> > > - KK
> >
> > Exactly. You can also try to tune the threshold
> > for interrupts as well.
> 
> I haven't tuned the threshhold, it is left it at 3/4. I ran
> the new qemu/vhost/guest, and the results for 1K, 2K and 16K
> are below. Note this is a different kernel version from my
> earlier test results. So, f.e., BW1 represents 2.6.39-rc2,
> the original kernel; while BW2 represents 2.6.37-rc5 (MST's
> kernel).

Weird. My kernel is actually 2.6.39-rc2. So which is which?

> This also isn't with the fixes you have sent just
> now. I will get a run with that either late tonight or
> tomorrow.

Shouldn't affect anything performance-wise.

> ________________________________________________________
>                    I/O size: 1K
> #     BW1     BW2 (%)        SD1       SD2 (%)
> ________________________________________________________
> 1     1723    3016 (75.0)    4.7       2.6 (-44.6)
> 2     3223    6712 (108.2)   18.0      7.1 (-60.5)
> 4     7223    8258 (14.3)    36.5      24.3 (-33.4)
> 8     8689    7943 (-8.5)    131.5     101.6 (-22.7)
> 16    8059    7398 (-8.2)    578.3     406.4 (-29.7)
> 32    7758    7208 (-7.0)    2281.4    1574.7 (-30.9)
> 64    7503    7155 (-4.6)    9734.0    6368.0 (-34.5)
> 96    7496    7078 (-5.5)    21980.9   15477.6 (-29.5)
> 128   7389    6900 (-6.6)    40467.5   26031.9 (-35.6)
> ________________________________________________________
> Summary:     BW: (4.4)     SD: (-33.5)
> 
> ________________________________________________________
>                  I/O size: 2K
> #     BW1     BW2 (%)        SD1       SD2 (%)
> ________________________________________________________
> 1     1608    4968 (208.9)   5.0       1.3 (-74.0)
> 2     3354    6974 (107.9)   18.6      4.9 (-73.6)
> 4     8234    8344 (1.3)     35.6      17.9 (-49.7)
> 8     8427    7818 (-7.2)    103.5     71.2 (-31.2)
> 16    7995    7491 (-6.3)    410.1     273.9 (-33.2)
> 32    7863    7149 (-9.0)    1678.6    1080.4 (-35.6)
> 64    7661    7092 (-7.4)    7245.3    4717.2 (-34.8)
> 96    7517    6984 (-7.0)    15711.2   9838.9 (-37.3)
> 128   7389    6851 (-7.2)    27121.6   18255.7 (-32.6)
> ________________________________________________________
> Summary:     BW: (6.0)     SD: (-34.5)
> 
> ________________________________________________________
>                   I/O size: 16K
> #     BW1     BW2 (%)        SD1       SD2 (%)
> ________________________________________________________
> 1     6684    7019 (5.0)     1.1       1.1 (0)
> 2     7674    7196 (-6.2)    5.0       4.8 (-4.0)
> 4     7358    8032 (9.1)     21.3      20.4 (-4.2)
> 8     7393    8015 (8.4)     82.7      82.0 (-.8)
> 16    7958    8366 (5.1)     283.2     310.7 (9.7)
> 32    7792    8113 (4.1)     1257.5    1363.0 (8.3)
> 64    7673    8040 (4.7)     5723.1    5812.4 (1.5)
> 96    7462    7883 (5.6)     12731.8   12119.8 (-4.8)
> 128   7338    7800 (6.2)     21331.7   21094.7 (-1.1)
> ________________________________________________________
> Summary:     BW: (4.6)     SD: (-1.5)
> 
> Thanks,
> 
> - KK