Date: Tue, 20 Nov 2018 14:58:41 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r340676 - in head/sys: kern sys Message-ID: <201811201458.wAKEwftP033152@repo.freebsd.org>
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Author: mjg Date: Tue Nov 20 14:58:41 2018 New Revision: 340676 URL: https://svnweb.freebsd.org/changeset/base/340676 Log: Implement unr64 Important users of unr like tmpfs or pipes can get away with just ever-increasing counters, making the overhead of managing the state for 32 bit counters a pessimization. Change it to an atomic variable. This can be further sped up by making the counts variable "allocate" ranges and store them per-cpu. Reviewed by: kib Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D18054 Modified: head/sys/kern/subr_unit.c head/sys/sys/systm.h Modified: head/sys/kern/subr_unit.c ============================================================================== --- head/sys/kern/subr_unit.c Tue Nov 20 14:52:43 2018 (r340675) +++ head/sys/kern/subr_unit.c Tue Nov 20 14:58:41 2018 (r340676) @@ -98,6 +98,19 @@ static struct mtx unitmtx; MTX_SYSINIT(unit, &unitmtx, "unit# allocation", MTX_DEF); +#ifdef UNR64_LOCKED +uint64_t +alloc_unr64(struct unrhdr64 *unr64) +{ + uint64_t item; + + mtx_lock(&unitmtx); + item = unr64->counter++; + mtx_unlock(&unitmtx); + return (item); +} +#endif + #else /* ...USERLAND */ #include <bitstring.h> Modified: head/sys/sys/systm.h ============================================================================== --- head/sys/sys/systm.h Tue Nov 20 14:52:43 2018 (r340675) +++ head/sys/sys/systm.h Tue Nov 20 14:58:41 2018 (r340676) @@ -523,6 +523,32 @@ int alloc_unr_specific(struct unrhdr *uh, u_int item); int alloc_unrl(struct unrhdr *uh); void free_unr(struct unrhdr *uh, u_int item); +#if defined(__mips__) || defined(__powerpc__) +#define UNR64_LOCKED +#endif + +struct unrhdr64 { + uint64_t counter; +}; + +static __inline void +new_unrhdr64(struct unrhdr64 *unr64, uint64_t low) +{ + + unr64->counter = low; +} + +#ifdef UNR64_LOCKED +uint64_t alloc_unr64(struct unrhdr64 *); +#else +static __inline uint64_t +alloc_unr64(struct unrhdr64 *unr64) +{ + + return (atomic_fetchadd_64(&unr64->counter, 1)); +} +#endif + void intr_prof_stack_use(struct thread *td, struct trapframe *frame); void counted_warning(unsigned *counter, const char *msg);
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