lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Fri, 22 Mar 2019 16:13:52 -0400 From: Carlos O'Donell <codonell@...hat.com> To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>, Carlos O'Donell <carlos@...hat.com> Cc: Florian Weimer <fweimer@...hat.com>, Joseph Myers <joseph@...esourcery.com>, Szabolcs Nagy <szabolcs.nagy@....com>, libc-alpha@...rceware.org, Thomas Gleixner <tglx@...utronix.de>, Ben Maurer <bmaurer@...com>, Peter Zijlstra <peterz@...radead.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Boqun Feng <boqun.feng@...il.com>, Will Deacon <will.deacon@....com>, Dave Watson <davejwatson@...com>, Paul Turner <pjt@...gle.com>, linux-kernel@...r.kernel.org, linux-api@...r.kernel.org Subject: Re: [PATCH 2/4] glibc: sched_getcpu(): use rseq cpu_id TLS on Linux On 2/12/19 2:42 PM, Mathieu Desnoyers wrote: > When available, use the cpu_id field from __rseq_abi on Linux to > implement sched_getcpu(). Fall-back on the vgetcpu vDSO if unavailable. > > Benchmarks: > > x86-64: Intel E5-2630 v3@...0GHz, 16-core, hyperthreading This patch looks good to me for master, but is blocked on patch 1/4 being reworked. Reviewed-by: Carlos O'Donell <carlos@...hat.com> > glibc sched_getcpu(): 13.7 ns (baseline) > glibc sched_getcpu() using rseq: 2.5 ns (speedup: 5.5x) > inline load cpuid from __rseq_abi TLS: 0.8 ns (speedup: 17.1x) > > Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com> > CC: Carlos O'Donell <carlos@...hat.com> > CC: Florian Weimer <fweimer@...hat.com> > CC: Joseph Myers <joseph@...esourcery.com> > CC: Szabolcs Nagy <szabolcs.nagy@....com> > CC: Thomas Gleixner <tglx@...utronix.de> > CC: Ben Maurer <bmaurer@...com> > CC: Peter Zijlstra <peterz@...radead.org> > CC: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com> > CC: Boqun Feng <boqun.feng@...il.com> > CC: Will Deacon <will.deacon@....com> > CC: Dave Watson <davejwatson@...com> > CC: Paul Turner <pjt@...gle.com> > CC: libc-alpha@...rceware.org > CC: linux-kernel@...r.kernel.org > CC: linux-api@...r.kernel.org > --- > sysdeps/unix/sysv/linux/sched_getcpu.c | 25 +++++++++++++++++++++++-- > 1 file changed, 23 insertions(+), 2 deletions(-) > > diff --git a/sysdeps/unix/sysv/linux/sched_getcpu.c b/sysdeps/unix/sysv/linux/sched_getcpu.c > index fb0d317f83..8bfb03778b 100644 > --- a/sysdeps/unix/sysv/linux/sched_getcpu.c > +++ b/sysdeps/unix/sysv/linux/sched_getcpu.c > @@ -24,8 +24,8 @@ > #endif > #include <sysdep-vdso.h> > > -int > -sched_getcpu (void) > +static int > +vsyscall_sched_getcpu (void) OK. > { > #ifdef __NR_getcpu > unsigned int cpu; > @@ -37,3 +37,24 @@ sched_getcpu (void) > return -1; > #endif > } > + > +#ifdef __NR_rseq > +#include <linux/rseq.h> > + > +extern __attribute__ ((tls_model ("initial-exec"))) > +__thread volatile struct rseq __rseq_abi; OK. > + > +int > +sched_getcpu (void) > +{ > + int cpu_id = __rseq_abi.cpu_id; > + > + return cpu_id >= 0 ? cpu_id : vsyscall_sched_getcpu (); OK. Impressive :-) > +} > +#else > +int > +sched_getcpu (void) > +{ > + return vsyscall_sched_getcpu (); OK. > +} > +#endif > -- Cheers, Carlos.
Powered by blists - more mailing lists