On Sun, Jan 12, 2020 at 11:08:02AM +0100, Mateusz Guzik wrote: > On 1/12/20, Konstantin Belousov <kostik...@gmail.com> wrote: > > On Sun, Jan 12, 2020 at 06:09:10AM +0000, Mateusz Guzik wrote: > >> Author: mjg > >> Date: Sun Jan 12 06:09:10 2020 > >> New Revision: 356656 > >> URL: https://svnweb.freebsd.org/changeset/base/356656 > >> > >> Log: > >> Add "panicked" boolean which can be tested instead of panicstr > >> > >> The test is performed all the time and reading entire panicstr to do it > >> wastes space. > > What space does it waste ? The space in the read-mostly section ? > > > > And what is the difference between reading a pointer vs. reading a byte ? > > CPU still has to read the whole cache line. > > > > Note the annotation with __read_frequently which groups fields. > > Currently it results in the following (with tail filled up from > __read_mostly): > > ---------------- > ffffffff80c01000 D hc_source_mask > ffffffff80c01004 D pti pti should be remove from __read_frequently, probably moving it to __read_mostly is fine, and changed to bool as well.
> ffffffff80c01008 D locks_delay > ffffffff80c0100c D locks_delay_retries > ffffffff80c0100e D locks_delay_loops > ffffffff80c01010 d fortuna_concurrent_read > ffffffff80c01011 D random_chachamode > ffffffff80c01012 D systrace_enabled > ffffffff80c01013 D lockstat_enabled > ffffffff80c01014 D dtrace_malloc_enabled > ffffffff80c01015 D racct_enable > ffffffff80c01016 D sdt_probes_enabled > ffffffff80c01017 D panicked > ffffffff80c01018 D kdb_active > ffffffff80c01019 D trap_enotcap > ffffffff80c0101a D audit_syscalls_enabled > ffffffff80c01020 D cam_dflags > ffffffff80c01028 d epoch_inited > ffffffff80c01030 d rs_epoch > ffffffff80c01038 d biozone > ---------------- > > Should panicstr land here it would avoidably take up 8 bytes instead of 1. > > -- > Mateusz Guzik <mjguzik gmail.com> _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
