Messages in this thread |  | | Date | Sun, 29 Apr 2001 16:18:59 -0600 | From | Richard Gooch <> | Subject | Re: X15 alpha release: as fast as TUX but in user space (fwd) |
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Ingo Oeser writes: > On Sun, Apr 29, 2001 at 12:48:06PM -0600, Richard Gooch wrote: > > Ingo Oeser writes: > > > There we have 10x faster memmove/memcpy/bzero for 1K blocks > > > granularity (== alignment is 1K and size is multiple of 1K), that > > > is done by the memory controller. > > This sounds different to me. Using the memory controller is (should > > be!) a privileged operation, thus it requires a system call. This is > > quite different from code in a magic page, which is excuted entirely > > in user-space. The point of the magic page is to avoid the syscall > > overhead. > > Yes, but we currently have more than 10K cycles for doing > memset of a page. If we do an syscall, we have around 600-900 > (don't know exactly), which is still less. > > The point is: The code in that "magic page" that considers the > tradeoff is KERNEL code, which is designed to care about such > trade-offs for that machine.
Um, yes. I don't disagree with that. I'm just saying the two issues are conceptually separate, and should be considered independently.
> Glibc never knows this stuff and shouldn't, because it is already > bloated.
True, true and true.
Regards,
Richard.... Permanent: rgooch@atnf.csiro.au Current: rgooch@ras.ucalgary.ca - 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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