http://lwn.net/Articles/145973/ This is a special feed containing comments posted to the individual LWN article titled "How fast should HZ be?". hourly 2 http://lwn.net/Articles/149617/rss 2005-08-29T20:22:15+00:00 rlrevell This is called a "singing capacitor". It happens because the greed of OEMs drives them to use increasingly cheap components. Windows uses a base timer frequency of 100HZ and that's all the OEMs test with so the problem isn't apparent under that OS.<br> http://lwn.net/Articles/147501/rss 2005-08-14T21:52:59+00:00 mikec There is another issue at work here which I have never taken the time to fully understand, but google tells me I am far from alone...<br> <p> 1000Hz Kernels make my laptop sound card whine!<br> <p> 100Hz whine far less if at all...<br> <p> I found this little gem a few years ago and various laptops I have had whine more or less with default kernels and changing this setting always seems to help. <br> <p> It makes some "seat of the pants" sense that the frequency of interrupts when the system is "idle" could interact with a poorly isolated sound card and cause undesired analog results... <br> <p> In the case of my current computer (dell 8600) it occurs:<br> a. running under windows<br> b. with the sound "muted" (under linux)<br> <p> The system whines when idle and quiets down when busy...<br> <p> I'd love to take the time to fully understand this some day, but in the mean time, I just change Hz and off I go computing quietly...<br> <p> /mike<br> http://lwn.net/Articles/147099/rss 2005-08-11T05:33:08+00:00 xorbe Certainly such a setup would be hand-tuned hopefully...<br> http://lwn.net/Articles/146379/rss 2005-08-05T09:33:50+00:00 tres Another reason to reduce the frequency is for servers with many virtual machines running since each one needs to service the interrupt and a machine with a thousand virtual machines running has to service ((1000 + 1) * Hz) timer interrupts. That is excessive when most of the virtual machines might be idle.<br> http://lwn.net/Articles/146340/rss 2005-08-04T21:40:24+00:00 jrigg Reducing HZ from 1000 to 100 gives around 7% power saving. That could be significant on a laptop, but presumably 250 will save less. Perhaps a simpler way of saving power would be to use less bloated software ;)<br>