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authorMiao Xie <miaox@cn.fujitsu.com>2008-04-28 00:54:56 -0400
committerIngo Molnar <mingo@elte.hu>2008-05-05 17:56:18 -0400
commitcb4ad1ffc7c0d8ea7dc8cd8ba303d83551716d46 (patch)
tree79f6b1fe971a270e5e009d695d2bf998936197c8 /fs/devpts
parent712555ee4f873515612f89554ad1a3fda5fa887e (diff)
sched: fair-group: fix a Div0 error of the fair group scheduler
When I echoed 0 into the "cpu.shares" file, a Div0 error occured. We found it is caused by the following calling. sched_group_set_shares(tg, shares) set_se_shares(tg->se[i], shares/nr_cpu_ids) __set_se_shares(se, shares) div64_64((1ULL<<32), shares) When the echoed value was less than the number of processores, the result of the sentence "shares/nr_cpu_ids" was 0, and then the system called div64() to divide the result, the Div0 error occured. It is unnecessary that the shares value is divided by nr_cpu_ids, I think. Because in the function __update_group_shares_cpu() and init_tg_cfs_entry(), the shares value isn't divided by nr_cpu_ids when setting shares of the sched entity. This patch fixes this bug. And echoing ULONG_MAX value into cpu.shares also causes Div0 error, so we set a macro MAX_SHARES to limit the max value of shares. Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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