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    SubjectRe: 2.2.18Pre Lan Performance Rocks!
    On Mon, Oct 30, 2000 at 11:27:04AM +0100, Ingo Molnar wrote:
    > On Mon, 30 Oct 2000, Jeff V. Merkey wrote:
    > > For example, if you put a MOV EAX, CR3; MOV CR3, EAX; in a context
    > > switching path, on a PPro 200, you can do about 35,000 context
    > > switches/second
    > in 2.4 & Xeons we can do more than 100,000 context switches/second, and
    > that is more than enough. But the point is: network IO performance does
    > not depend on context switching speed too much. Also, in Linux we are
    > using global pages which makes kernel-space TLBs persistent even across
    > CR3 flushes.

    This is putrid. NetWare does 353,00,000/second on a Xenon, pumping out
    gobs of packets in between them. MANOS does 857,000,000/second. This
    is terrible. No wonder it's so f_cking slow!!!

    > > [...] There's also the use of segment registers all over the place to
    > > copy from kernel to user and user to kernel space memory. [...]
    > we do not use the fs segment register for user-space copies anymore,
    > neither in 2.2, nor in 2.4. You must be reading old books and probably
    > forgot to cross-check with the kernel source? :-)

    ds: and es: are both used in copy-to-user and copy-from-user and they get

    > > [...] Having the fast paths you mention does help a lot, but it's the
    > > fact that this goes on at all that will make it tough to walk into a
    > > NetWare shop with Linux and rip out NetWare servers and replace them
    > > unless we look at a NetWare vs. NetLinux (that's what we call it! a
    > > NetWare-like Linux platform).
    > the worst thing you can do is to mis-identify performance problems and
    > spend braincells on the wrong problem. The problems limiting Linux network
    > scalability have been identified during the last 12 months by a small
    > team, and solved in TUX. TUX is a fileserver, it shouldnt be alot of work
    > to enable it for (TCP-only?) netware serving. It's *done*, Jeff, it's not
    > a hypotetical thing, it's here, it works and it performs.

    NetWare is here too, and it handles 5000+ file and print users, Linux does not.
    Let's fix it. I know why NetWare is fast. Let's apply some of the same
    principles and see what happens. Love to have you involved.

    > Ingo
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