Call for re(4) TSO/VLAN testers
Pyun YongHyeon
pyunyh at gmail.com
Mon Nov 13 16:01:33 PST 2006
On Mon, Nov 13, 2006 at 04:37:57PM +0100, Pieter de Goeje wrote:
> On Saturday 11 November 2006 02:10, Pyun YongHyeon wrote:
> > With TSO you can see reduced system load while large file transfers
> > is in progress. Please test the patch and report any unusual things
> > you've found.
>
> Idle time has increased from 0% to 25% with this patch while sustaining the
> transferrate (520Mbit/s) previously reached with iperf.
> With the patch the number of interrupts/sec. was halved from 32K to 16K.
>
> The test was performed on a fresh current without any tuning but with debug
> support removed.
>
> System details:
> CPU: AMD Sempron(tm) 2400+ (1659.95-MHz 686-class CPU)
> re0 at pci0:9:0: class=0x020000 card=0x816910ec chip=0x816910ec rev=0x10
> hdr=0x00
> vendor = 'Realtek Semiconductor'
> device = 'RTL8169 Gigabit Ethernet Adapter'
>
> The receiving end was probably limiting the transferrate.
>
Thanks for reporting.
ATM re(4) uses still small number of Tx descriptors(i.e. 64 entries)
due to the hardware limitation of 8139C+. 8169 family can have
up to 1024 Tx descriptors. If we want to use more Tx descriptors
on 8169 the internal structure should be modified to support both
8139C+ and 8169. I guess it would require major Tx path overhaul.
Because I have just plain PCI 8169 hardware I can't sure increasing
number of Tx descriptors on re(4) help Tx performance of the driver.
I guess 64 Tx descriptors are not sufficient to saturate giga bit
link.
Would please try attached patch and report the performance of patched
re(4) driver?
--
Regards,
Pyun YongHyeon
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