Date: Tue, 2 Jan 2018 00:11:56 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r327480 - in stable/11/sys: cddl/dev/sdt kern sys Message-ID: <201801020011.w020Buhk026508@repo.freebsd.org>
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Author: mjg Date: Tue Jan 2 00:11:56 2018 New Revision: 327480 URL: https://svnweb.freebsd.org/changeset/base/327480 Log: MFC r324867,r324869: sdt: whack unused SDT_PROBE_ENABLED ============= sdt: make all sdt probe sites test one variable This saves on cache misses at the expense of a slight grow of .text. Note this is a bandaid for lack of hotpatching. Modified: stable/11/sys/cddl/dev/sdt/sdt.c stable/11/sys/kern/kern_sdt.c stable/11/sys/sys/sdt.h Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/cddl/dev/sdt/sdt.c ============================================================================== --- stable/11/sys/cddl/dev/sdt/sdt.c Tue Jan 2 00:07:28 2018 (r327479) +++ stable/11/sys/cddl/dev/sdt/sdt.c Tue Jan 2 00:11:56 2018 (r327480) @@ -76,6 +76,8 @@ static void sdt_kld_unload_try(void *, struct linker_f static MALLOC_DEFINE(M_SDT, "SDT", "DTrace SDT providers"); +static int sdt_probes_enabled_count; + static dtrace_pattr_t sdt_attr = { { DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON }, { DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN }, @@ -208,6 +210,9 @@ sdt_enable(void *arg __unused, dtrace_id_t id, void *p probe->sdtp_lf->nenabled++; if (strcmp(probe->prov->name, "lockstat") == 0) lockstat_enabled++; + sdt_probes_enabled_count++; + if (sdt_probes_enabled_count == 1) + sdt_probes_enabled = true; } static void @@ -217,6 +222,9 @@ sdt_disable(void *arg __unused, dtrace_id_t id, void * KASSERT(probe->sdtp_lf->nenabled > 0, ("no probes enabled")); + sdt_probes_enabled_count--; + if (sdt_probes_enabled_count == 0) + sdt_probes_enabled = false; if (strcmp(probe->prov->name, "lockstat") == 0) lockstat_enabled--; probe->id = 0; Modified: stable/11/sys/kern/kern_sdt.c ============================================================================== --- stable/11/sys/kern/kern_sdt.c Tue Jan 2 00:07:28 2018 (r327479) +++ stable/11/sys/kern/kern_sdt.c Tue Jan 2 00:11:56 2018 (r327480) @@ -37,6 +37,7 @@ SDT_PROVIDER_DEFINE(sdt); * dtrace_probe() when it loads. */ sdt_probe_func_t sdt_probe_func = sdt_probe_stub; +volatile bool __read_frequently sdt_probes_enabled; /* * This is a stub for probe calls in case kernel DTrace support isn't Modified: stable/11/sys/sys/sdt.h ============================================================================== --- stable/11/sys/sys/sdt.h Tue Jan 2 00:07:28 2018 (r327479) +++ stable/11/sys/sys/sdt.h Tue Jan 2 00:11:56 2018 (r327480) @@ -80,13 +80,14 @@ #include <sys/cdefs.h> #include <sys/linker_set.h> +extern volatile bool sdt_probes_enabled; + #ifndef KDTRACE_HOOKS #define SDT_PROVIDER_DEFINE(prov) #define SDT_PROVIDER_DECLARE(prov) #define SDT_PROBE_DEFINE(prov, mod, func, name) #define SDT_PROBE_DECLARE(prov, mod, func, name) -#define SDT_PROBE_ENABLED(prov, mod, func, name) 0 #define SDT_PROBE(prov, mod, func, name, arg0, arg1, arg2, arg3, arg4) #define SDT_PROBE_ARGTYPE(prov, mod, func, name, num, type, xtype) @@ -161,14 +162,13 @@ SET_DECLARE(sdt_argtypes_set, struct sdt_argtype); #define SDT_PROBE_DECLARE(prov, mod, func, name) \ extern struct sdt_probe sdt_##prov##_##mod##_##func##_##name[1] -#define SDT_PROBE_ENABLED(prov, mod, func, name) \ - __predict_false((sdt_##prov##_##mod##_##func##_##name->id)) - #define SDT_PROBE(prov, mod, func, name, arg0, arg1, arg2, arg3, arg4) do { \ - if (__predict_false(sdt_##prov##_##mod##_##func##_##name->id)) \ + if (__predict_false(sdt_probes_enabled)) { \ + if (__predict_false(sdt_##prov##_##mod##_##func##_##name->id)) \ (*sdt_probe_func)(sdt_##prov##_##mod##_##func##_##name->id, \ (uintptr_t) arg0, (uintptr_t) arg1, (uintptr_t) arg2, \ (uintptr_t) arg3, (uintptr_t) arg4); \ + } \ } while (0) #define SDT_PROBE_ARGTYPE(prov, mod, func, name, num, type, xtype) \
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