On Fri, 2019-09-06 at 01:19 +0000, Philip Paeps wrote: > Author: philip > Date: Fri Sep 6 01:19:31 2019 > New Revision: 351918 > URL: https://svnweb.freebsd.org/changeset/base/351918 > > Log: > riscv: default to HZ=100 > > Most current RISC-V development platforms are not fast enough to > benefit > from the increased granularity provided by HZ=1000. > > Sponsored by: Axiado > > Modified: > head/sys/kern/subr_param.c > > Modified: head/sys/kern/subr_param.c > ===================================================================== > ========= > --- head/sys/kern/subr_param.c Fri Sep 6 00:06:55 2019 (r351 > 917) > +++ head/sys/kern/subr_param.c Fri Sep 6 01:19:31 2019 (r351 > 918) > @@ -61,7 +61,7 @@ __FBSDID("$FreeBSD$"); > */ > > #ifndef HZ > -# if defined(__mips__) || defined(__arm__) > +# if defined(__mips__) || defined(__arm__) || defined(__riscv) > # define HZ 100 > # else > # define HZ 1000 >
This seems like a bad idea. I've run a 90mhz armv4 chip with HZ=1000 and didn't notice any performance hit from doing so. Almost all arm kernel config files set HZ as an option, so that define doesn't do much for arm these days. It probably does still set HZ for various mips platforms. I would think 1000 is appropriate for anything modern running at 200mhz or more. Setting it to 100 has the bad side effect of making things like msleep(), tsleep(), and pause() (which show up in plenty of drivers) all have a minimum timeout of 10ms, which is a long long time on modern hardware. What benefit do you think you'll get from the lower number? -- Ian _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
