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由 Matt Fleming 提交于
There's no diagnostic checks for figuring out when we've accidentally missed update_rq_clock() calls. Let's add some by piggybacking on the rq_*pin_lock() wrappers. The idea behind the diagnostic checks is that upon pining rq lock the rq clock should be updated, via update_rq_clock(), before anybody reads the clock with rq_clock() or rq_clock_task(). The exception to this rule is when updates have explicitly been disabled with the rq_clock_skip_update() optimisation. There are some functions that only unpin the rq lock in order to grab some other lock and avoid deadlock. In that case we don't need to update the clock again and the previous diagnostic state can be carried over in rq_repin_lock() by saving the state in the rq_flags context. Since this patch adds a new clock update flag and some already exist in rq::clock_skip_update, that field has now been renamed. An attempt has been made to keep the flag manipulation code small and fast since it's used in the heart of the __schedule() fast path. For the !CONFIG_SCHED_DEBUG case the only object code change (other than addresses) is the following change to reset RQCF_ACT_SKIP inside of __schedule(), - c7 83 38 09 00 00 00 movl $0x0,0x938(%rbx) - 00 00 00 + 83 a3 38 09 00 00 fc andl $0xfffffffc,0x938(%rbx) Suggested-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NMatt Fleming <matt@codeblueprint.co.uk> Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org> Cc: Byungchul Park <byungchul.park@lge.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jan Kara <jack@suse.cz> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@unitn.it> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Mike Galbraith <efault@gmx.de> Cc: Mike Galbraith <umgwanakikbuti@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Rik van Riel <riel@redhat.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Cc: Yuyang Du <yuyang.du@intel.com> Link: http://lkml.kernel.org/r/20160921133813.31976-8-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
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