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Thanks to Christope, I re-examined those ~10 cases, and that should be refactored by just dropping msec_to_jiffies() part, not replacing by sec_to_jiffies(). >>>> >>> >>> Those seem to be mistakes. const*HZ is a seconds-denominated timeout, >>> being passed to msecs_to_jiffies() which will treat it as a >>> millisecond-denominated timeout resulting in an excessively long >>> timeout. I suppose that's better than a too-short timeout, and >>> apparently it's been working fine all along since hardware responds >>> before the too-long timeout expires. Half of them are in >>> drivers/scsi/arcmsr/arcmsr_hba.c and the pattern has apparently been >>> there since 2010. >> >> my point was that, the default value of HZ is 1000, and most of the code >> that is just `$value*HZ` was meant as "$value seconds, in ms unit". > > I can't follow you here. The default value of HZ is 250 as far as I can > see. as default I understand "the value that is effective for those that don't tweak", not necessarily "the fallback that will be used when not set by any other means". On my RedHat and Fedora boxes it's 1000. > > Regardless, HZ is the number of jiffies per second, nothing else. That is true. But the name is wrong. > >> >> Same for HZ/const, HZ/2 being 500ms. >> >> HZ is awful in that it is not 1s but 1/s, but it was easy to abuse the >> value in simple context. > > Why is that awful ? so, 1Hertz = 1/1s == once per second, something happening twice per second, with freq of 2Hz, repeats each HZ/2 jiffies https://en.wikipedia.org/wiki/Hertz the #define name should be really JHZ -> JIFFIES_PER_SECOND > > HZ is a nice macro that gives you the number of ticks per second, so > that you are able to easily calculate the number of ticks for a given > duration, regardless of the configured number of ticks per second. Again, technically true, but default being eq to number of msec in sec, causes it to bite.