When I set a scan to Low priority, is this the same as setting a process to Windows XP’s low priority using the task manager? Some apps allow the user to throttle the CPU usage, and they call it “priority”. Windows XP’s priority differs from throttling in that it allows a process to consume all the CPU if there are no competing demands. Avast’s scan seems to use significantly less than 50% CPU even if there are no competing demands on the CPU. However, I’m not sure if that’s due to an I/O limit.
It gives a higher priority over other processes and would as the settings says The higher the priority, the less time the scan will take, but will use more resources.
I generally have mine set to High as I don’t have a resource issue, but considering your other topic; if you ever get the scheduled scan working other processes would be dormant so increasing the priority/resources shouldn’t be an issue.
I understand the general idea of prioritization, but I’m still unclear whether Avast actually uses prioritization or just throttling of the CPU usage by the scan.
If it is true prioritization, then it should run at full speed in the absence of other significant competing demands by other processes. So if there are no other processes making significant demands on the CPU, then the scan performance will not be much affected by the priority because it will use most of the CPU cycles.
On the other hand, if it is throttling, then regardless of whether there are other demands on the CPU, the scan will not be allowed to use more of the CPU than the maximum percentage for that throttling level. For example, if the maximum for Low level is 35%, then the scan will not be allowed to use more than 35% of the CPU even if no other processes make significant demands on the remaining 65%. It might, however, use less than 35% if other demands are high. Believe it or not, some malware scanners do this (though because of the idle CPU capacity, it makes far less sense to me than true prioritization). I forgot which antimalware does this, but I think it is the big-name one with a huge presence in corporate organization and governments. It also uses approximately half the RAM on my venerable machine, hence I no longer use it.
I was wondering which of these two schemes are meant by Avast “prioritizaion”.
Does the cpu usage differ if you set low Vs. Normal or high?
Are there any tasks competing for the cpu ?
No, avast! scan priorities are not directly related to Windows priorities.
If you set it to Low, it will be somewhat slower even if no other processes are using the CPU. I’d recommend to stick with Normal.
OK, thanks. Is it correct to say that Avast prioritization has the end effect of being a blend of Windows style prioritization and CPU usage throttling?