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Message-ID: <54059BAA.1080307@oracle.com> Date: Tue, 02 Sep 2014 06:27:54 -0400 From: Sowmini Varadhan <sowmini.varadhan@...cle.com> To: David Miller <davem@...emloft.net> CC: raghuram.kothakota@...cle.com, netdev@...r.kernel.org Subject: Re: [PATCH net-next 2/2] sunvnet: Re-check for a VIO_DESC_READY data descriptor after short udelay() On 09/01/2014 11:47 PM, David Miller wrote: > > If there were no more packets coming, this is wasted useless polling > time in atomic context. turns out that this gives a 20-30% perf improvement for tests like iperf. when there are no more packets coming, the extra 12 microsecond delay is not that big of a deal anyway. The point was that the extra 12 micro-second tax in the quiescent network state is less expensive than exiting interrupt context, taking another interrupt and doing another ldc_read, when there is actually a burst of packets. notice that there are many other such udelay() loops elsewhere in the code. I can remove the retries and submit patch 1/1 again later today. > > Everything should be event based, and we should not be compensating > and making sacrifices for a producer slower than we are as a consumer. > -- > 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 > -- 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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