[lkml]   [2006]   [Nov]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [rfc patch] i386: don't save eflags on task switch
    On Sat, Nov 04, 2006 at 11:09:42AM -0800, Zachary Amsden wrote:
    > Every processor I've ever measured it on, popf is slower. On P4, for
    > example, pushf is 6 cycles, and popf is 54. On Opteron, it is 2 / 12.
    > On Xeon, it is 7 / 91.

    pushf has to wait until all flag dependancies can be resolved. On the
    P4 with >100 instructions in flight, that can take a long time. Popf
    on the other hand has no dependancies on outstanding instructions as it
    resets the machine state.

    "Time is of no importance, Mr. President, only life is important."
    Don't Email: <>.
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2006-11-05 04:59    [W:0.018 / U:10.340 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site