Messages in this thread | | | Date | Mon, 10 Feb 2014 13:35:35 -0800 (PST) | From | David Rientjes <> | Subject | Re: [RFC PATCH V5] mm readahead: Fix readahead fail for no local memory and limit readahead pages |
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On Mon, 10 Feb 2014, Raghavendra K T wrote:
> So I understood that you are suggesting implementations like below > > 1) I do not have problem with the below approach, I could post this in > next version. > ( But this did not include 4k limit Linus mentioned to apply) > > unsigned long max_sane_readahead(unsigned long nr) > { > unsigned long local_free_page; > int nid; > > nid = numa_mem_id(); > > /* > * We sanitize readahead size depending on free memory in > * the local node. > */ > local_free_page = node_page_state(nid, NR_INACTIVE_FILE) > + node_page_state(nid, NR_FREE_PAGES); > return min(nr, local_free_page / 2); > } > > 2) I did not go for below because Honza (Jan Kara) had some > concerns for 4k limit for normal case, and since I am not > the expert, I was waiting for opinions. > > unsigned long max_sane_readahead(unsigned long nr) > { > unsigned long local_free_page, sane_nr; > int nid; > > nid = numa_mem_id(); > /* limit the max readahead to 4k pages */ > sane_nr = min(nr, MAX_REMOTE_READAHEAD); > > /* > * We sanitize readahead size depending on free memory in > * the local node. > */ > local_free_page = node_page_state(nid, NR_INACTIVE_FILE) > + node_page_state(nid, NR_FREE_PAGES); > return min(sane_nr, local_free_page / 2); > } >
I have no opinion on the 4KB pages, either of the above is just fine.
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