Add simd metadata in /proc on Linux

Too many times, people's performance problems have amounted to
"somehow your SIMD support isn't working", and determining that
at runtime is difficult to describe to people.

This adds a /proc/spl/kstat/zfs/simd node, which exposes
metadata about which instructions ZFS thinks it can use,
on AArch64 and x86_64 Linux, to make investigating things
like this much easier.

Signed-off-by: Rich Ercolani <[email protected]>

include/os/freebsd/spl/sys/simd.h

@@ -50,4 +50,7 @@
 #define	kfpu_fini()		do {} while (0)
 #endif
 
+#define	simd_stat_init()	0
+#define	simd_stat_fini()	0
+
 #endif

include/os/linux/kernel/linux/simd.h

@@ -45,4 +45,8 @@
 #define	kfpu_fini()		((void) 0)
 
 #endif
+
+void simd_stat_init(void);
+void simd_stat_fini(void);
+
 #endif /* _LINUX_SIMD_H */

lib/libspl/include/sys/simd.h

@@ -592,4 +592,7 @@ zfs_isa207_available(void)
 
 #endif
 
+extern void simd_stat_init(void);
+extern void simd_stat_fini(void);
+
 #endif /* _LIBSPL_SYS_SIMD_H */

lib/libzpool/Makefile.am

@@ -55,6 +55,7 @@ nodist_libzpool_la_SOURCES = \
 	module/zcommon/zfeature_common.c \
 	module/zcommon/zfs_comutil.c \
 	module/zcommon/zfs_deleg.c \
+	module/zcommon/simd_stat.c \
 	module/zcommon/zfs_fletcher.c \
 	module/zcommon/zfs_fletcher_aarch64_neon.c \
 	module/zcommon/zfs_fletcher_avx512.c \

module/Kbuild.in

@@ -236,6 +236,7 @@ ZCOMMON_OBJS := \
 	zfs_comutil.o \
 	zfs_deleg.o \
 	zfs_fletcher.o \
+	simd_stat.o \
 	zfs_fletcher_superscalar.o \
 	zfs_fletcher_superscalar4.o \
 	zfs_namecheck.o \

module/zcommon/simd_stat.c

@@ -0,0 +1,167 @@
+#include <sys/zfs_context.h>
+#include <sys/kstat.h>
+#include <sys/simd.h>
+
+
+#ifdef _KERNEL
+#ifdef __linux__
+#include <linux/simd.h>
+#endif /* __linux__ */
+kstat_t *simd_stat_kstat;
+#endif /* _KERNEL */
+
+#ifdef _KERNEL
+/* shut up making this more lines helps nobody */
+/* CSTYLED */
+#define SIMD_STAT_PRINT(s, feat, val)	kmem_scnprintf(s + off, 4095 - off, "%-16s\t%1d\n", feat, (val))
+
+static int
+simd_stat_kstat_data(char *buf, size_t size, void *data)
+{
+	(void) data;
+
+	static char simd_stat_kstat_payload[4096] = {0};
+	static int off = 0;
+#ifdef __linux__
+	if (off == 0) {
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "kfpu_allowed", kfpu_allowed());
+#ifdef __x86__
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "kfpu", HAVE_KERNEL_FPU);
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "kfpu_internal", HAVE_KERNEL_FPU_INTERNAL);
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "__kernel_fpu", HAVE_UNDERSCORE_KERNEL_FPU);
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sse", zfs_sse_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sse2", zfs_sse2_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sse3", zfs_sse3_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "ssse3", zfs_ssse3_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sse41", zfs_sse4_1_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sse42", zfs_sse4_2_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx", zfs_avx_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx2", zfs_avx2_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512f", zfs_avx512f_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512cd", zfs_avx512cd_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512er", zfs_avx512er_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512pf", zfs_avx512pf_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512bw", zfs_avx512bw_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512dq", zfs_avx512dq_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512vl", zfs_avx512vl_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512ifma", zfs_avx512ifma_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "avx512vbmi", zfs_avx512vbmi_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "ymm", __ymm_enabled());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "zmm", __zmm_enabled());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "bmi1", zfs_bmi1_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "bmi2", zfs_bmi2_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "aes", zfs_aes_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "pclmulqdq", zfs_pclmulqdq_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "movbe", zfs_movbe_available());
+
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "osxsave", boot_cpu_has(X86_FEATURE_OSXSAVE));
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "xsaves", static_cpu_has(X86_FEATURE_XSAVES));
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "xsaveopt", static_cpu_has(X86_FEATURE_XSAVEOPT));
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "xsave", static_cpu_has(X86_FEATURE_XSAVE));
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "fxsr", static_cpu_has(X86_FEATURE_FXSR));
+#endif /* __x86__ */
+#if defined(__arm__) || defined(__aarch64__)
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "kernel_neon", HAVE_KERNEL_NEON);
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "kernel_mode_neon", CONFIG_KERNEL_MODE_NEON);
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "neon", zfs_neon_available());
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sha256", zfs_sha256_available());
+#if defined(__aarch64__)
+		/*
+		 * This technically can exist on 32b ARM but we don't
+		 * define hooks to check for it and I didn't want to
+		 * learn enough ARM ASM to add one.
+		 */
+		off += SIMD_STAT_PRINT(simd_stat_kstat_payload,
+		    "sha512", zfs_sha512_available());
+#endif /* __aarch64__ */
+#endif /* __arm__ */
+	}
+
+	// we need one more for the trailing newline, or this prints grossly.
+	off += 1;
+	kmem_scnprintf(buf, MIN(off, size), "%s", simd_stat_kstat_payload);
+#endif /* __linux__ */
+	return (0);
+}
+#endif /* _KERNEL */
+
+void
+simd_stat_init(void)
+{
+	static boolean_t simd_stat_initialized = B_FALSE;
+
+	if (!simd_stat_initialized) {
+#if defined(_KERNEL)
+		/* Install kstats for all implementations */
+		simd_stat_kstat = kstat_create("zfs", 0, "simd", "misc",
+		    KSTAT_TYPE_RAW, 0, KSTAT_FLAG_VIRTUAL);
+
+
+		if (simd_stat_kstat != NULL) {
+			simd_stat_kstat->ks_data = (void*)(uintptr_t)1;
+			simd_stat_kstat->ks_ndata = 1;
+			simd_stat_kstat->ks_flags |= KSTAT_FLAG_NO_HEADERS;
+			kstat_set_raw_ops(simd_stat_kstat,
+			    NULL,
+			    simd_stat_kstat_data,
+			    NULL);
+			kstat_install(simd_stat_kstat);
+		}
+#endif /* _KERNEL */
+	}
+	/* Finish initialization */
+	simd_stat_initialized = B_TRUE;
+}
+
+void
+simd_stat_fini(void)
+{
+#if defined(_KERNEL)
+	if (simd_stat_kstat != NULL) {
+		kstat_delete(simd_stat_kstat);
+		simd_stat_kstat = NULL;
+	}
+#endif
+}
+
+#ifdef _KERNEL
+EXPORT_SYMBOL(simd_stat_init);
+EXPORT_SYMBOL(simd_stat_fini);
+#endif

module/zcommon/zfs_prop.c

@@ -41,6 +41,7 @@
 #include <sys/zfs_ioctl.h>
 #include <sys/zfs_znode.h>
 #include <sys/dsl_crypt.h>
+#include <sys/simd.h>
 
 #include "zfs_prop.h"
 #include "zfs_deleg.h"
@@ -1063,6 +1064,9 @@ EXPORT_SYMBOL(zfs_kfpu_fpregs);
 extern int __init zcommon_init(void);
 extern void zcommon_fini(void);
 
+extern void simd_stat_init(void);
+extern void simd_stat_fini(void);
+
 int __init
 zcommon_init(void)
 {
@@ -1071,13 +1075,15 @@ zcommon_init(void)
 		return (error);
 
 	fletcher_4_init();
+	simd_stat_init();
 
 	return (0);
 }
 
 void
 zcommon_fini(void)
 {
+	simd_stat_fini();
 	fletcher_4_fini();
 	kfpu_fini();
 }