Author: mjg Date: Sun Sep 10 19:00:38 2017 New Revision: 323393 URL: https://svnweb.freebsd.org/changeset/base/323393
Log: Move vmmeter atomic counters into dedicated cache lines Prior to the change they were subject to extreme false sharing. In particular this change shaves about 3 seconds real time of -j 80 buildkernel. Reviewed by: alc, markj Differential Revision: https://reviews.freebsd.org/D12281 Modified: head/sys/sys/vmmeter.h head/sys/vm/vm_meter.c Modified: head/sys/sys/vmmeter.h ============================================================================== --- head/sys/sys/vmmeter.h Sun Sep 10 18:08:25 2017 (r323392) +++ head/sys/sys/vmmeter.h Sun Sep 10 19:00:38 2017 (r323393) @@ -60,6 +60,12 @@ struct vmtotal { #if defined(_KERNEL) || defined(_WANT_VMMETER) #include <sys/counter.h> +#ifdef _KERNEL +#define VMMETER_ALIGNED __aligned(CACHE_LINE_SIZE) +#else +#define VMMETER_ALIGNED +#endif + /* * System wide statistics counters. * Locking: @@ -126,14 +132,15 @@ struct vmmeter { u_int v_free_target; /* (c) pages desired free */ u_int v_free_min; /* (c) pages desired free */ u_int v_free_count; /* (f) pages free */ - u_int v_wire_count; /* (a) pages wired down */ - u_int v_active_count; /* (q) pages active */ u_int v_inactive_target; /* (c) pages desired inactive */ - u_int v_inactive_count; /* (q) pages inactive */ - u_int v_laundry_count; /* (q) pages eligible for laundering */ u_int v_pageout_free_min; /* (c) min pages reserved for kernel */ u_int v_interrupt_free_min; /* (c) reserved pages for int code */ u_int v_free_severe; /* (c) severe page depletion point */ + u_int v_wire_count VMMETER_ALIGNED; /* (a) pages wired down */ + u_int v_active_count VMMETER_ALIGNED; /* (a) pages active */ + u_int v_inactive_count VMMETER_ALIGNED; /* (a) pages inactive */ + u_int v_laundry_count VMMETER_ALIGNED; /* (a) pages eligible for + laundering */ }; #endif /* _KERNEL || _WANT_VMMETER */ Modified: head/sys/vm/vm_meter.c ============================================================================== --- head/sys/vm/vm_meter.c Sun Sep 10 18:08:25 2017 (r323392) +++ head/sys/vm/vm_meter.c Sun Sep 10 19:00:38 2017 (r323393) @@ -56,7 +56,7 @@ __FBSDID("$FreeBSD$"); #include <vm/vm_object.h> #include <sys/sysctl.h> -struct vmmeter vm_cnt = { +struct vmmeter __exclusive_cache_line vm_cnt = { .v_swtch = EARLY_COUNTER, .v_trap = EARLY_COUNTER, .v_syscall = EARLY_COUNTER, _______________________________________________ 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"
