lkml.org 
[lkml]   [2005]   [Sep]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [discuss] Re: [PATCH] x86-64: Fix bad assumption that dualcore cpus have synced TSCs
    On Wed, Sep 21, 2005 at 10:15:08AM -0500, Ray Bryant wrote:
    > On Tuesday 20 September 2005 23:03, Daniel Jacobowitz wrote:
    >
    > >
    > > FYI, at least I have reproduced this without powernow loaded.
    >
    > There are cases that we are aware of where the TSC will count slower while the
    > processor is halted. This can make TSC's get out of sync on dual cores.

    Ok thanks for the confirmation. I guess John's patch is ok then.
    Drawback is much slower to extremly slow gettimeofday (depending
    if the chipset/BIOS has usable HPET, most seem not to)

    >
    > I wonder if you can reproduce this problem while also running a pair of cpu
    > bound tasks on your dual core box. If you can't, then this is the culprit.
    >
    > In general, however, on multisocket systems, you can't depend on TSC's being
    > synchronized between sockets, so all of this is moot. We just have to deal
    > with it.

    We handle this, but single socket dual core was special cased because
    I was told previously it should be ok.

    -Andi
    -
    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/

    \
     
     \ /
      Last update: 2005-09-21 17:06    [W:3.949 / U:0.684 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site