Linux下通过修改网卡驱动的参数调整Intel网卡的性能

迈不过友情╰ 2022-08-07 01:51 339阅读 0赞

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       Intel的千兆网卡驱动(e1000.ko)加载的时候可以加上几个参数，如下： 
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       insmod e1000.ko &lt;parameter&gt;=&lt;value&gt; 
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       下面列出paramerter中和性能相关的几个以及他们的取值范围和默认值。 
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      <span style="color: #ff0000;">InterruptThrottleRate</span> 
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       范围：100-100000 (0=off, 1=dynamic) 
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       默认：0 
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       注：不支持82542, 82543, 82545, 82544芯片 
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      <span style="color: #ff0000;">RxDescriptors</span> 
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       范围：80-256 for 82542 and 82543-based adapters 
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       &nbsp;&nbsp;&nbsp;&nbsp; 80-4096 for all other supported adapters 
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       默认:256 
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      <span style="color: #ff0000;">RxIntDelay</span> 
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       范围：0-65535 (0=off) 
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       默认：0 
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      <span style="color: #ff0000;">RxAbsIntDelay</span> 
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        范围：0-65535 (0=off) 
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        默认：128 
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       <span style="color: #ff0000;">TxDescriptors</span> 
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        范围：80-256 for 82542 and 82543-based adapters 
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        &nbsp;&nbsp;&nbsp;&nbsp; 80-4096 for all other supported adapters 
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        默认：256 
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        <span style="color: #ff0000;">TxIntDelay</span> 
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         范围：0-65535 (0=off) 
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         默认：64 
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        <span style="color: #ff0000;">TxAbsIntDelay</span> 
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          范围：0-65535 (0=off) 
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          默认：64 
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       其中各种*IntDelay的单位是：1.024 microseconds 
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       我们可以根据网卡的性能和cpu，内存，pci总线等不同来调整它们的值，另外可以编译网卡驱动的时候修改编译选项：NAPI和NO_NAPI。 
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       make CFLAGS_EXTRA=-DCONFIG_E1000_NAPI 
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       我找到一个关于如何修改这些参数取值得例子不过是英文的，怕翻译的不好，还是放上来原文吧。 
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      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><strong><span style="font-size: 16pt; color: blue; mso-font-kerning: 0pt;">A Sample Configuration</span></strong></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Some example settings are described below. These numbers are for illustration purposes only. For</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">optimal performance, the exact controller configuration is best determined through actual</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">experimentation.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">The discussion below assumes that software is optimizing for full-size frames of 1538 bytes.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">The calculations below make use of the following facts:</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">Gigabit Ethernet operates at 1.0 Gb/s or 1,000,000,000 bits per second. At this speed, the time required to transmit or receive a single bit (in other words, the bit-time) is 1.0 nanosecond.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">A full-size Ethernet frame requires 1538 bytes (12,304 bits) of bandwidth:</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">—8-byte preamble and start-of-frame delimiter</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">—14-byte Ethernet header</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">—1500-byte payload</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">—4-byte FCS</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">—12-byte inter-packet gap</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">The controller can transmit or receive a full-size frame every 12.3 microseconds or approximately 81,000 packets per second.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><strong><span style="font-size: 14pt; color: blue; mso-font-kerning: 0pt;">Absolute Timers</span></strong></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Configuring the absolute timers is typically a matter of determining the desired interrupt rate or the</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">desired number of packets per interrupt. To receive approximately 3000 interrupts per second,</span></span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">software would configure the absolute timers to interrupt every 333 microseconds.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Alternately, to receive approximately 50 packets per interrupt, </span></span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">the controller must interruptapproximately 1620 times per second (81,000 packets-per-second at 50 packets-per-interrupt).</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Software would then configure the absolute timers to interrupt every 617 microseconds.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><strong><span style="font-size: 14pt; color: blue; mso-font-kerning: 0pt;">Packet Timers</span></strong></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Experiments have shown that values between 20 and 40 microseconds work well for the packet</span></span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">timers.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Software might set the packet timers to expire after 2 full-length packet-times, or approximately 25</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">microseconds. The packet timers would then expire when throughput falls below about 333Mbps</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">(two unused packet-times follow every packet arrival, so approximately one-third of the total</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">bandwidth is in use). At greater levels of utilization, the packet timers would likely chain</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">repeatedly until the one of the absolute timers expired.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><strong><span style="font-size: 14pt; color: blue; mso-font-kerning: 0pt;">Interrupt Throttle Timer</span></strong></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Configuring the throttle timer is simply a question of determining the desired maximum interrupt</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">rate. As described earlier, software may realize better results by setting the throttle timer to</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">interrupt slightly more often than desired to reduce unnecessary latencies.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">For typical applications, software might configure the controller to interrupt no more than 5000</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">times per second.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">Different operating systems and environments will be capable of sustaining different maximum</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">interrupt rates. Experiments have demonstrated that Microsoft Windows-based operating systems</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">perform best when the device interrupts between 4,000 and 12,000 times per second. Linux-based</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">operating systems appear to perform best with an interrupt rate between 1,000 and 8,000 interrupts</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">per second. Other operating systems will perform differently.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><strong><span style="font-size: 14pt; color: blue; mso-font-kerning: 0pt;">Additional Tuning Considerations</span></strong></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">The example configuration described above will require modifications to suit the intended</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">environment. The following factors may influence the tuning of the interrupt moderationparameters:</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">The latency associated with scheduling an interrupt handler. Larger scheduling latencies</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">imply larger packet latencies. Lower interrupt delays may be required in these situations </span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;"><span style="font-family: Times New Roman;">to avoid overrun conditions and excessive per-packet delays.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">The cost associated with handling an interrupt. In OS with low-cost interrupts, higher interrupt rates may be acceptable. In OS with high-cost interrupts, lower interrupt rates may be required.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">The expected mixture of packet sizes. The preceding discussion assumes that software is optimizing for full-size frames. Optimizing for small packets or for a variety of packet sizes requires recalculating the expected packet rate.</span></span></p> 
      <p style="margin: 0cm 0cm 0pt; text-align: left; mso-layout-grid-align: none;"><span style="font-family: Times New Roman;"><span style="font-size: 12pt; color: black; mso-font-kerning: 0pt;">•</span><span style="font-size: 10pt; color: black; mso-font-kerning: 0pt;">The expected network utilization. High utilization implies high traffic rates, which makes the controller more susceptible to overrun conditions if it delays interrupts too long.</span></span></p> 
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