[lkml]   [2007]   [Apr]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRE: Fw: [PATCH] ia64: race flushing icache in do_no_page path

    -----Original Message-----
    From: Nick Piggin []
    Sent: Friday, April 27, 2007 7:00 PM
    Cc: Mike Stroyan; Andrew Morton; Hugh Dickins; Luck, Tony;;
    Subject: Re: Fw: [PATCH] ia64: race flushing icache in do_no_page path

    Rohit Seth wrote:
    >> You mean by user space? If so, then it is user space responsibility to
    >> do the appropriate operations (like flush icache in this case).

    >No, I mean places that set PG_arch_1. flush_dcache_page. This can happen
    >for mapped pages in write, splice, install_arg_page looks questionable,
    direct IO...

    If a user is requesting kernel to do (for example) write on a page that is
    already mapped with execute and write permissions then it should be treated
    as if the user space is doing modifications to that page. There is no
    change in protections so lazy_prot_mmu_update shouldn't be called even
    though PG_arch_1 is (I think) set. Does it answer your concern?

    >What if you were to say remove all the PG_arch_1 code, and do
    >something really simple like flush icache in
    >flush_dcache_page? Would performance suffer horribly?

    On Itanium, I think it will have some performance penalty (horrible or not I
    don't know) as you will be invalidating the caches more often. And they
    alsways look for last 0.1% performance that they can get.


    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: 2007-04-28 20:03    [W:0.020 / U:16.380 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site