Messages in this thread | | | Date | Thu, 15 Nov 2007 08:30:33 +1100 | From | Paul Mackerras <> | Subject | Re: [perfmon] Re: [perfmon2] perfmon2 merge news |
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Nick Piggin writes:
> What I really mean is a readv-like syscall, but one that also > vectorises the file offset. Maybe this is useful enough as a generic > syscall that also helps Paul's example...
I've sometimes thought it would be useful to have a "transaction" system call that is like a write + read combined into one:
int transaction(int fd, char *req, size_t req_nb, char *reply, size_t reply_nb);
as a way to provide a general request/reply interface for special files.
> Of course, I guess this all depends on whether the atomicity is an > important requirement. If not, you can obviously just do it with > multiple read syscalls...
That would take N system calls instead of one, which could have a performance impact if you need to read the counters frequently (which I believe you do in some performance monitoring situations).
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