Re: Call for re(4) TSO/VLAN testers

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