From: Miao Xie Date: Mon, 28 Apr 2008 04:54:56 +0000 (+0800) Subject: sched: fair-group: fix a Div0 error of the fair group scheduler X-Git-Tag: v2.6.26-rc2~62^2~4 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cb4ad1ffc7c0d8ea7dc8cd8ba303d83551716d46;p=pandora-kernel.git 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 Acked-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed