Hi Wolfram-san,

> From: Yoshihiro Shimoda, Sent: Monday, May 13, 2019 6:46 PM
<snip>
> > That also means, for the sys-dmac and Gen2, we then use 512 for the
> > IOMMU case and 32 (default TMIO value) for the non IOMMU case. My
> > understanding is that SYS DMAC can handle 512 in both cases. Maybe it
> > makes sense then to make an incremental patch setting the max_segs value
> > explicitly to 512 in the sys-dmac driver for Gen2?
> 
> I also think SYS DMAC can handle 512 segments. However, I'm not sure
> it can improve the performance or not though. Anyway, an incremental patch
> makes sense if needed, I think.

I measured the performance on R-Car H2 Lager. It seems 512 segments improve
the sequential input to 5%. May I make an incremental patch on the patch series?
What do you think?

Best regards,
Yoshihiro Shimoda

--
kernel v5.1-rc7 + local patches + sdr104,,,,,,,,,,,,,,,,,,,,,,,,,,
Buildroot 2019.02.1,,,,,,,,,,,,,,,,,,,,,,,,,,
Bonnie++ 1.03e : bonnie\+\+ -d ./ -s 2048 -r 1024 -b -u 
root,,,,,,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,,,,,,
environment,Size,Sequential Output - per char (K/sec),<- (CPU %),Sequential 
Output - block (K/sec),<- (CPU %),Sequential Output - rewrite (K/sec),<- (CPU 
%),Sequential Input - per char (K/sec),<- (CPU %),Sequential Input ? block 
(K/sec),<- (CPU %),Random seeks,<- (CPU %),files,Sequential Create,<- (CPU 
%),Sequential Read,<- (CPU %),Sequential Delete,<- (CPU %),Random Create,<- 
(CPU %),Random Read,<- (CPU %),Random Delete,<- (CPU %)
max_segs_32_sys_dmac,2G,19651,45,18122,7,11612,5,31417,56,34344,6,20.9,0,16,183,1,+++++,+++,195,1,198,2,+++++,+++,195,2
max_segs_512_sys_dmac,2G,18728,43,18273,8,12405,5,33524,61,34158,6,21.0,0,16,184,1,+++++,+++,189,1,198,2,+++++,+++,194,2

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