[lkml]   [2017]   [Sep]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRE: [PATCH RFC 3/5] Add KSZ8795 switch driver
From: Andrew Lunn
> Sent: 28 September 2017 20:34
> > There are 34 counters. In normal case using generic bus I/O or PCI to read them
> > is very quick, but the switch is mostly accessed using SPI, or even I2C. As the SPI
> > access is very slow.
> How slow is it? The Marvell switches all use MDIO. It is probably a
> bit faster than I2C, but it is a lot slower than MMIO or PCI.
> ethtool -S lan0 takes about 25ms.

Is the SPI access software bit-banged?
Doing that with software delays isn't friendly to the rest of the system.
(Hardware guys please note...)

One possibility is to rate-limit the stats reading.
Then an application cannot completely 'hog' the SPI bandwidth.


 \ /
  Last update: 2017-09-29 11:16    [W:0.109 / U:1.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site