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Re: 2.4 kernel performance?

The serial drivers are differently, some features of the elinux driver
has not been ported to 2.4 yet.
One thing that is different is the DMA timeout handling,
in 2.4 it's 8 jiffies (MAX_FLUSH_TIME) and not configurable as
it is in elinux (it probably should be configurable).
If you have short messages used for handshaking this could have
a big impact.
You can try decreasing MAX_FLUSH_TIME in arch/cris/drivers/serial.c
and see if that helps.


----- Original Message -----
From: <matthew.hook@xxxxxxx.nz>
To: <dev-etrax@xxxxxxx.com>
Sent: Tuesday, May 08, 2001 06:24
Subject: 2.4 kernel performance?

> Has anyone noticed whether the 2.4 kernel on the Etrax 100LX has
> significantly slower
> performance than uClinux?
> I've spent the best part of an afternoon observing that code compiled
> running on uClinux
> runs about 4 times faster than code on the 2.4.... however, it might be
> e.g. the com port
> drivers under 2.4... my software basically reads data from one com port
> writes it to another
> and vice versa, but the throughput has dropped by more than 1/4 on Linux
> 2.4.
> Has anyone noticed anything similar?