Re: headsup: swap_pager.c

From: Dan Nelson (dnelson_at_allantgroup.com)
Date: 08/01/03

  • Next message: M. Warner Losh: "Re: headsup: swap_pager.c" 
    Date: Fri, 1 Aug 2003 09:41:09 -0500
To: Poul-Henning Kamp <phk@phk.freebsd.dk>

    In the last episode (Aug 01), Poul-Henning Kamp said:
    > In message <xzpel0568cn.fsf@dwp.des.no>, Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?=
    > writes:
    > >"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
    > >> The thing you overlook is that often when things gets paged out,
    > >> the system is short on memory and therefore more likely to not do
    > >> anything productive, whereas when things gets paged in, there are
    > >> a better chance of some other process being able to use the CPU
    > >> time productively. If we did predictive pageouts like some of the
    > >> "serious" mainfram OS's this would be less true.
    > >
    > >How hard would it be to get the kernel to write the pages "most
    > >likely to be swapped out" to swap in the idle loop, to save time if
    > >/ when they actually need to be swapped out later?
    >
    > I don't know :-)
    >
    > Quite frankly, given the sizes of RAM we see these days, I think that
    > paging optimizations may be largely a thing of the past.

    RAM is like disk space; if it's there, users will consume it. If you
    have 8GB of RAM, someone will write a program that needs 2gb of RAM,
    then someone else will decide to run that program in 5 vtys (speaking
    from experience here).

    Predictive swapping would be neat. 

    -- 
	Dan Nelson
	dnelson@allantgroup.com
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  • Next message: M. Warner Losh: "Re: headsup: swap_pager.c"

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