Date: Wed, 11 May 2005 20:41:24 +0530 From: Subhro <subhro.kar@gmail.com> To: Tuomo Latto <djv@mbnet.fi> Cc: FreeBSD Stable <freebsd-stable@freebsd.org> Subject: Re: xl(4) & polling Message-ID: <4282209C.3070507@gmail.com> In-Reply-To: <4281C1FC.800@mbnet.fi> References: <20050511051016.93990.qmail@web54002.mail.yahoo.com> <42819770.9070007@gmail.com> <4281C1FC.800@mbnet.fi>
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This is a multi-part message in MIME format. --------------050305000602040908090708 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 5/11/2005 13:57, Tuomo Latto wrote: > Subhro wrote: > ... > >> In Device Polled systems, the NIC does not generate any interrupt at >> all. Instead whenever the packets arrive at a Network interface, they >> are captured and put into a queue. The kernel scheduler checks the >> quese at regular intervals and processes the packets which are >> waiting. This interval is adjusted by the "options HZ=x" kernel option. >> >> If the value of x is very high, there may eb two scenarios. In the >> first scenario, the queue may fill up and subsequent packets are >> dropped. In this case retransmission of the packets are required. In >> the second scenario, the packets would be held up for excessive long >> times which defeats the entire purpose of Device Polling. If the >> value of x is very low, the scheduler would check the queue >> frequently and would again defeat the entire idea of Device Polling. > > > It's the other way around. Large values indicate larger polling frequency > thus amounting to more checks. Or at least the name of the option would > suggest that anyway. > > Silly me :(. I meant something, typed something else. Its indeed the other way round. Thanks to everyone who pointed this out. Regards S. --------------050305000602040908090708--
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