Date: Wed, 21 Sep 2005 16:54:13 +0800 From: "Mao Shou Yan" <david.mao@thomson.net> To: <freebsd-net@freebsd.org> Subject: About guideline of parameters tuning while in polling mode. Message-ID: <31021C278A7A6B4AB95E9A085C3552181CE58F@bjngsmail01>
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Hi, everybody Can anyone give some guidelines on tuning the following parameters when the system is in polling mode and works in high throughput network environment. Thanks a lot! =20 =20 /* * EM_TIDV - Transmit Interrupt Delay Value=20 * Valid Range: 0-65535 (0=3Doff) * Default Value: 64 * This value delays the generation of transmit interrupts in units of * 1.024 microseconds. Transmit interrupt reduction can improve CPU * efficiency if properly tuned for specific network traffic. If the * system is reporting dropped transmits, this value may be set too high * causing the driver to run out of available transmit descriptors. */ #define EM_TIDV 64 =20 /* * EM_TADV - Transmit Absolute Interrupt Delay Value (Not valid for 82542/82543/82544) * Valid Range: 0-65535 (0=3Doff) * Default Value: 64 * This value, in units of 1.024 microseconds, limits the delay in which a * transmit interrupt is generated. Useful only if EM_TIDV is non-zero, * this value ensures that an interrupt is generated after the initial * packet is sent on the wire within the set amount of time. Proper tuning, * along with EM_TIDV, may improve traffic throughput in specific * network conditions. */ #define EM_TADV 64 =20 /* * EM_RDTR - Receive Interrupt Delay Timer (Packet Timer)=20 * Valid Range: 0-65535 (0=3Doff) * Default Value: 0 * This value delays the generation of receive interrupts in units of 1.024 * microseconds. Receive interrupt reduction can improve CPU efficiency if * properly tuned for specific network traffic. Increasing this value adds * extra latency to frame reception and can end up decreasing the throughput * of TCP traffic. If the system is reporting dropped receives, this value * may be set too high, causing the driver to run out of available receive * descriptors. * * CAUTION: When setting EM_RDTR to a value other than 0, adapters * may hang (stop transmitting) under certain network conditions. * If this occurs a WATCHDOG message is logged in the system event log. * In addition, the controller is automatically reset, restoring the * network connection. To eliminate the potential for the hang * ensure that EM_RDTR is set to 0. */ #define EM_RDTR 0 =20 /* * Receive Interrupt Absolute Delay Timer (Not valid for 82542/82543/82544) * Valid Range: 0-65535 (0=3Doff) * Default Value: 64 * This value, in units of 1.024 microseconds, limits the delay in which a * receive interrupt is generated. Useful only if EM_RDTR is non-zero, * this value ensures that an interrupt is generated after the initial * packet is received within the set amount of time. Proper tuning, * along with EM_RDTR, may improve traffic throughput in specific network * conditions. */ #define EM_RADV 64 =20
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