3 ms·
OK, I really don't know anything about assembly/OSes, but if the price of going to kernel mode with sysenter/syscall is smaller than a not that pricey(the artic
by pcr910303 7y ago
OK, I really don't know anything about assembly/OSes, but if the price of going to kernel mode with sysenter/syscall is smaller than a not that pricey(the article says it's less than a single 64-bit integer division), does that mean microkernels can utilize that to improve performance?
What are the shortcomings of the method compared to interrupts?
- monocasa 7y agoThe l4 variants think so. Unfortunately Spectre was sort of a pain and now they have to switch page table roots a bunch.
- dfox 7y agoOn microkernels the issue is usually not with syscall performance but with essentially every operation causing a task switch which on i386 causes TLB flush (which in post-Spectre days seems somewhat moot) and in many cases involves interacting with task scheduler. (QNX uses interesting hack to sidestep this: the message passing interface does not really pass messages, but is simply cross-addressspace call/return that in essence temporarily moves a thread to different process without rescheduling anything)