Hi everybody, On Wed, 8 Mar 2006, Jean Delvare wrote: > The only data I am missing now is the memory used by each additional > sysfs file we create. We need to know, as Hans objected that too many > sysfs files could have a negative impact on memory consumption. I dug I've just created a couple sysfs files in order to find out, and the conclusion is that each additional sysfs file reduces the remaining free memory by something on the order of 90-95 bytes. It turns out that the memory reported by 'free' varies quite a bit between calls, which disturbs somewhat the precision of this measurement. I had to create 10000 sysfs files in order to get a statistically significant result. Now this result is correct on the 10% level, which I think is good enough for our discussion. For this experiment, I used the same callback function for all sysfs files, so each additional file has just one SENSOR_DEVICE_ATTR struct definition and a device_create_file() call, but no extra supporting code. This is the typical situation for the individual alarm files, I guess. With current DRAM prices, 100 extra bytes correspond to extra costs of around 1e-5 EUR or USD for each additional file, which I think is tolerable. Best regards, Hartmut
