Messages in this thread Patch in this message | | | Date | Fri, 4 Nov 2005 08:26:28 +0100 | From | Ingo Molnar <> | Subject | [patch] swapin rlimit |
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* Andrew Morton <akpm@osdl.org> wrote:
> Similarly, that SGI patch which was rejected 6-12 months ago to kill > off processes once they started swapping. We thought that it could be > done from userspace, but we need a way for userspace to detect when a > task is being swapped on a per-task basis.
wouldnt the clean solution here be a "swap ulimit"?
I.e. something like the 2-minute quick-hack below (against Linus-curr).
Ingo
--- implement a swap ulimit: RLIMIT_SWAP.
setting the ulimit to 0 causes any swapin activity to kill the task. Setting the rlimit to 0 is allowed for unprivileged users too, since it is a decrease of the default RLIM_INFINITY value. I.e. users could run known-memory-intense jobs with such an ulimit set, and get a guarantee that they wont put the system into a swap-storm.
Note: it's just swapin that causes the SIGKILL, because at swapout time it's hard to identify the originating task. Pure swapouts and a buildup in the swap-cache is not punished, only actual hard swapins. I didnt try too hard to make the rlimit particularly finegrained - i.e. right now we only know 'zero' and 'infinity' ...
Signed-off-by: Ingo Molnar <mingo@elte.hu>
include/asm-generic/resource.h | 4 +++- mm/memory.c | 13 +++++++++++++ 2 files changed, 16 insertions(+), 1 deletion(-)
Index: linux/include/asm-generic/resource.h =================================================================== --- linux.orig/include/asm-generic/resource.h +++ linux/include/asm-generic/resource.h @@ -44,8 +44,9 @@ #define RLIMIT_NICE 13 /* max nice prio allowed to raise to 0-39 for nice level 19 .. -20 */ #define RLIMIT_RTPRIO 14 /* maximum realtime priority */ +#define RLIMIT_SWAP 15 /* maximum swapspace for task */ -#define RLIM_NLIMITS 15 +#define RLIM_NLIMITS 16 /* * SuS says limits have to be unsigned. @@ -86,6 +87,7 @@ [RLIMIT_MSGQUEUE] = { MQ_BYTES_MAX, MQ_BYTES_MAX }, \ [RLIMIT_NICE] = { 0, 0 }, \ [RLIMIT_RTPRIO] = { 0, 0 }, \ + [RLIMIT_SWAP] = { RLIM_INFINITY, RLIM_INFINITY }, \ } #endif /* __KERNEL__ */ Index: linux/mm/memory.c =================================================================== --- linux.orig/mm/memory.c +++ linux/mm/memory.c @@ -1647,6 +1647,18 @@ void swapin_readahead(swp_entry_t entry, } /* + * Crude first-approximation swapin-avoidance: if there is a zero swap + * rlimit then kill the task. + */ +static inline void check_swap_rlimit(void) +{ + unsigned long limit = current->signal->rlim[RLIMIT_SWAP].rlim_cur; + + if (limit != RLIM_INFINITY) + force_sig(SIGKILL, current); +} + +/* * We enter with non-exclusive mmap_sem (to exclude vma changes, * but allow concurrent faults), and pte mapped but not yet locked. * We return with mmap_sem still held, but pte unmapped and unlocked. @@ -1667,6 +1679,7 @@ static int do_swap_page(struct mm_struct entry = pte_to_swp_entry(orig_pte); page = lookup_swap_cache(entry); if (!page) { + check_swap_rlimit(); swapin_readahead(entry, address, vma); page = read_swap_cache_async(entry, vma, address); if (!page) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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