Messages in this thread | | | Subject | Negative "ios_in_flight" in the 2.4 kernel | From | "M. Edward Borasky" <> | Date | Tue, 21 Dec 2004 21:05:36 -0800 |
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I've been looking at some "iostat" data from a 2.4.26 machine. The device utilizations are 100 percent, even when the disk is idle, which is mathematically impossible. By doing some digging, I discovered this is a kernel bug, caused by "hd->ios_in_flight" going negative. The relevant code appears to my untrained eyes to be in drivers/block/ll_rw_blk.c, specifically
static inline void down_ios(struct hd_struct *hd) { disk_round_stats(hd); --hd->ios_in_flight; }
static inline void up_ios(struct hd_struct *hd) { disk_round_stats(hd); ++hd->ios_in_flight; }
Question: wouldn't a simple refusal to decrement ios_in_flight in "down_ios" if it's zero fix this, or am I missing something?
Ed Borasky znmeb@cesmail.net
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