Missatge de Thomas Munro <thomas.mu...@gmail.com> del dia dj., 16 de maig 2019 a les 13:09: > > On Wed, May 15, 2019 at 1:13 PM Andres Freund <and...@anarazel.de> wrote: > > > I've run a quick pgbench benchmark: > > > > > > *Without* disabling SMT, for readonly pgbench, I'm seeing regressions > > > between 7-11%, depending on the size of shared_buffers (and some runtime > > > variations). That's just on my laptop, with an i7-6820HQ / Haswell CPU. > > > I'd be surprised if there weren't adversarial loads with bigger > > > slowdowns - what gets more expensive with the mitigations is syscalls. > > This stuff landed in my FreeBSD 13.0-CURRENT kernel, so I was curious > to measure it with and without the earlier mitigations. On my humble > i7-8550U laptop with the new 1.22 microcode installed, with my usual > settings of PTI=on and IBRS=off, so far MDS=VERW gives me ~1.5% loss > of TPS with a single client, up to 4.3% loss of TPS for 16 clients, > but it didn't go higher when I tried 32 clients. This was a tiny > scale 10 database, though in a quick test it didn't look like it was > worse with scale 100. > > With all three mitigations activated, my little dev machine has gone > from being able to do ~11.8 million baseline syscalls per second to
Did you mean "1.8"? > ~1.6 million, or ~1.4 million with the AVX variant of the mitigation. > > Raw getuid() syscalls per second: > > PTI IBRS MDS=off MDS=VERW MDS=AVX > ===== ===== ======== ======== ======== > off off 11798658 4764159 3274043 > off on 2652564 1941606 1655356 > on off 4973053 2932906 2339779 > on on 1988527 1556922 1378798 > > pgbench read-only transactions per second, 1 client thread: > > PTI IBRS MDS=off MDS=VERW MDS=AVX > ===== ===== ======== ======== ======== > off off 19393 18949 18615 > off on 17946 17586 17323 > on off 19381 19015 18696 > on on 18045 17709 17418 > > pgbench -M prepared read-only transactions per second, 1 client thread: > > PTI IBRS MDS=off MDS=VERW MDS=AVX > ===== ===== ======== ======== ======== > off off 35020 34049 33200 > off on 31658 30902 30229 > on off 35445 34353 33415 > on on 32415 31599 30712 > > pgbench -M prepared read-only transactions per second, 4 client threads: > > PTI IBRS MDS=off MDS=VERW MDS=AVX > ===== ===== ======== ======== ======== > off off 79515 76898 76465 > off on 63608 62220 61952 > on off 77863 75431 74847 > on on 62709 60790 60575 > > pgbench -M prepared read-only transactions per second, 16 client threads: > > PTI IBRS MDS=off MDS=VERW MDS=AVX > ===== ===== ======== ======== ======== > off off 125984 121164 120468 > off on 112884 108346 107984 > on off 121032 116156 115462 > on on 108889 104636 104027 > > time gmake -s check: > > PTI IBRS MDS=off MDS=VERW MDS=AVX > ===== ===== ======== ======== ======== > off off 16.78 16.85 17.03 > off on 18.19 18.81 19.08 > on off 16.67 16.86 17.33 > on on 18.58 18.83 18.99 > > -- > Thomas Munro > https://enterprisedb.com > > -- Albert Cervera i Areny http://www.NaN-tic.com Tel. 93 553 18 03
