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Date: Fri, 08 Jun 2007 07:31:07 -0400 From: jamal <hadi@...erus.ca> To: Evgeniy Polyakov <johnpol@....mipt.ru> Cc: Krishna Kumar2 <krkumar2@...ibm.com>, Gagan Arneja <gaagaan@...il.com>, netdev@...r.kernel.org, Rick Jones <rick.jones2@...com>, Sridhar Samudrala <sri@...ibm.com>, David Miller <davem@...emloft.net>, Robert Olsson <Robert.Olsson@...a.slu.se> Subject: Re: [WIP][PATCHES] Network xmit batching On Fri, 2007-08-06 at 12:38 +0400, Evgeniy Polyakov wrote: > On Thu, Jun 07, 2007 at 06:23:16PM -0400, jamal (hadi@...erus.ca) wrote: > > I believe both are called with no lock. The idea is to avoid the lock > > entirely when unneeded. That code may end up finding that the packet [..] > + netif_tx_lock_bh(odev); > + if (!netif_queue_stopped(odev)) { > + > + idle_start = getCurUs(); > + pkt_dev->tx_entered++; > + ret = odev->hard_batch_xmit(&odev->blist, odev); [..] > The same applies to *_gso case. > You missed an important piece which is grabbing of __LINK_STATE_QDISC_RUNNING > Without lock that would be wrong - it accesses hardware. We are achieving the goal of only a single CPU entering that path. Are you saying that is not good enough? > I only saw results Krishna posted, Ok, sorry - i thought you saw the git log or earlier results where other things are captured. > and i also do not know, what service demand is :) >>From the explanation seems to be how much cpu was used while sending. Do you have any suggestions for computing cpu use? in pktgen i added code to count how many microsecs were used in transmitting. > Result looks good, but I still do not understand how it appeared, that > is why I'm not that excited about idea - I just do not know it in > details. To add to KKs explanation on other email: Essentially the value is in amortizing the cost of barriers and IO per packet. For example the queue lock is held/released only once per X packets. DMA kicking which includes both a PCI IO write and mbs is done only once per X packets. There are still a lot of room for improvement of such IO; cheers, jamal - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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