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    SubjectRe: Time for a pre-patch-2.0.31-3? (buffer/cache patch included)
    >> >     mm/vmscan.c 
    > ...
    > > change try_to_free_page() in some point to have a more aggressive

    This version of try_to_free_page() is my own ... it's not in 2.1.xx.
    The old version works like the agricultural three-filed system (with the
    fields shrink_mmap, shm_swap, and swap_out). Only if current field fails
    the switch to the next field follows ... a social behaviour. This is what
    kswapd should do ... and kswapd has no problems if try_to_free_page()
    fails. If a process needs a page the chance to get a free page is
    higher in the next unused field ... this is what this version of
    try_to_free_page() do if called with wait=1 ... an egoistic behaviour.

    ... just like in real life :-)

    > > swapping strategy in low memory situations.
    > > change in swap_tick(): wakeup kswapd more often in low memory
    > > situations (adapted from 2.1.xx)
    > ...
    > These two changes from 2.1 wil kill machines that run out of swap/have
    > slow processors - take a look at the changes I made to vmscan.c in
    > for kswapd() and
    > swap_tick() -- those changes should improve things on systems which
    > swap a lot as they keep the swap more behaviour introduced in 2.1.3?,
    > but try to be gentle and not eat 100% cpu when we do start swapping. Like
    > I've said - it's a temporary fix until mm is reworked to be more
    > deterministic.

    Hmmm ... the only change in kswapd() I've done is:

    while (1) {
    kswapd_awake = 0;
    current->signal = 0;
    kswapd_awake = 1;
    /* Do the background pageout: */
    for (i=0; i < kswapd_ctl.maxpages; i++)
    - try_to_free_page(GFP_KERNEL, 0, 0);
    + try_to_free_page(GFP_KERNEL, 0, (nr_free_pages < min_free_pages));

    this should not be a problem, shouldn't it?

    Only the change in swap_tick()

    - next_swap_jiffies = jiffies + swapout_interval;
    + /* low on memory, we need to start swapping soon */
    + if(last_wakeup_low)
    + next_swap_jiffies = jiffies;
    + else
    + next_swap_jiffies = jiffies + swapout_interval;

    may cause a problem. If I understand your hint correct, kswapd will be waked
    up in a loop without running any other process if the last call can not free a
    physical page due to a low swap space.

    One question more: Does my version of try_to_free_page() run cause
    any trouble with the version of your kswapd/swap_tick solution
    given in


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