On Fri, 13 Jul 2018 11:02:13 +0800, bing zhu said: > Iâm trying to write a simple fs in user space,if memcpy is slower than > kernel , i think it's unfair,as for only cpu for my task, > it's a bit of arbitrary ï¼i just want my task not interrupted during a > specific time is that possible ?
Not getting interrupted is an *entirely* different issue than making memcpy fast. Note that in general, systems code should be able to deal with interruptions during most parts of the code, and locking used and disabling pre-emption for sections of code that can't deal with being interrupted. Remember that if your filesystem code turns off interrupts for long enough, you can start losing things like I/O completions. Fortunately for those who write systems code, the vast majority of interrupts are totally transparent to the vast majority of the kernel code. And if you're doing a file system in userspace, you're going to fail to notice hundreds or even thousands of interrupts happening. If you don't believe me, 'cat /proc/interrupts', and realize that userspace didn't notice *any* of them happening.
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