Messages in this thread | | | Date | Thu, 15 Aug 2002 21:42:25 -0400 | From | Benjamin LaHaise <> | Subject | Re: aio-core why not using SuS? [Re: [rfc] aio-core for 2.5.29 (Re: async-io API registration for 2.5.29)] |
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On Fri, Aug 16, 2002 at 01:54:59AM +0200, Andrea Arcangeli wrote: > the window a kernel window inside a preempt_disable and a __cli() will > have a goodness effect in a number of cases, but I don't think it > matters significantly because you still need some gettimeofday in > userspace (or clock_gettime if that matters, clock_gettime infact is > even worse than gettimeofday due its certainly lower resolution).
Yeah, I've come full circle back to the relative timeout point of view. By grabbing a copy of jiffies at the beginning of the function the race with preempt can be avoided.
> Now reading the SuS specifications I also like less and less our current > kernel API of this sumbit_io, the SuS does exactly what I suggested > originally that is aio_read/aio_write/aio_fsync as separate calls. So > the merging effect mentioned by Ben cannot be taken advantage of by the > kernel anyways because userspace will issue separate calls for each > command.
Read it again. You've totally missed lio_listio. Also keep in mind what happens with 4G/4G split for x86 which are needed to address the kernel virtual memory starvation issues.
-ben -- "You will be reincarnated as a toad; and you will be much happier." - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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