On Tue, 2020-09-22 at 11:13 +0800, huang ying wrote: > On Tue, Sep 22, 2020 at 10:02 AM Rik van Riel <riel@xxxxxxxxxxx> > wrote: > > Check whether a swap page was obtained instantaneously, for example > > because it is in zswap, or on a very fast IO device which uses busy > > waiting, and we did not wait on IO to swap in this page. > > If no IO was needed to get the swap page we want, kicking off > > readahead > > on surrounding swap pages is likely to be counterproductive, > > because the > > extra loads will cause additional latency, use up extra memory, and > > chances > > are the surrounding pages in swap are just as fast to load as this > > one, > > making readahead pointless. > > > > Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx> > > --- > > mm/swap_state.c | 14 +++++++++++--- > > 1 file changed, 11 insertions(+), 3 deletions(-) > > > > diff --git a/mm/swap_state.c b/mm/swap_state.c > > index aacb9ba53f63..6919f9d5fe88 100644 > > --- a/mm/swap_state.c > > +++ b/mm/swap_state.c > > @@ -637,6 +637,7 @@ static struct page > > *swap_cluster_read_one(swp_entry_t entry, > > struct page *swap_cluster_readahead(swp_entry_t entry, gfp_t > > gfp_mask, > > struct vm_fault *vmf) > > Why not do this for swap_vma_readahead() > too? swap_cluster_read_one() > can be used in swap_vma_readahead() too. Good point, I should do the same thing for swap_vma_readahead() as well. Let me do that and send in a version 2 of the series. -- All Rights Reversed.
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