A GEOM cache can speed up read performance by sending fixed size

read requests to its consumer.  It has been developed to address
the problem of a horrible read performance of a 64k blocksize FS
residing on a RAID3 array with 8 data components, where a single
disk component would only get 8k read requests, thus effectively
killing disk performance under high load.  Documentation will be
provided later.  I'd like to thank Vsevolod Lobko for his bright
ideas, and Pawel Jakub Dawidek for helping me fix the nasty bug.

1 files changed, 241 insertions, 0 deletions

diff --git a/sbin/geom/class/cache/geom_cache.c b/sbin/geom/class/cache/geom_cache.c
new file mode 100644
index 000000000000..19a0bf5a03fd
--- /dev/null
+++ b/sbin/geom/class/cache/geom_cache.c
@@ -0,0 +1,241 @@
+/*-
+ * Copyright (c) 2006 Ruslan Ermilov <ru@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <errno.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <strings.h>
+#include <libgeom.h>
+#include <geom/cache/g_cache.h>
+
+#include "core/geom.h"
+#include "misc/subr.h"
+
+
+uint32_t lib_version = G_LIB_VERSION;
+uint32_t version = G_CACHE_VERSION;
+
+static intmax_t blocksize_label = 65536;
+static intmax_t size_label = 100;
+static intmax_t blocksize_configure = 0;
+static intmax_t size_configure = 0;
+
+static void cache_main(struct gctl_req *req, unsigned flags);
+static void cache_clear(struct gctl_req *req);
+static void cache_dump(struct gctl_req *req);
+static void cache_label(struct gctl_req *req);
+
+struct g_command class_commands[] = {
+	{ "clear", G_FLAG_VERBOSE, cache_main, G_NULL_OPTS,
+	    "[-v] prov ..."
+	},
+	{ "configure", G_FLAG_VERBOSE, NULL,
+	    {
+		{ 'b', "blocksize", &blocksize_configure, G_TYPE_NUMBER },
+		{ 's', "size", &size_configure, G_TYPE_NUMBER },
+		G_OPT_SENTINEL
+	    },
+	    "[-v] [-b blocksize] [-s size] name"
+	},
+	{ "create", G_FLAG_VERBOSE | G_FLAG_LOADKLD, NULL,
+	    {
+		{ 'b', "blocksize", &blocksize_label, G_TYPE_NUMBER },
+		{ 's', "size", &size_label, G_TYPE_NUMBER },
+		G_OPT_SENTINEL
+	    },
+	    "[-v] [-b blocksize] [-s size] name prov"
+	},
+	{ "destroy", G_FLAG_VERBOSE, NULL,
+	    {
+		{ 'f', "force", NULL, G_TYPE_NONE },
+		G_OPT_SENTINEL
+	    },
+	    "[-fv] name ..."
+	},
+	{ "dump", 0, cache_main, G_NULL_OPTS,
+	    "prov ..."
+	},
+	{ "label", G_FLAG_VERBOSE | G_FLAG_LOADKLD, cache_main,
+	    {
+		{ 'b', "blocksize", &blocksize_label, G_TYPE_NUMBER },
+		{ 's', "size", &size_label, G_TYPE_NUMBER },
+		G_OPT_SENTINEL
+	    },
+	    "[-v] [-b blocksize] [-s size] name prov"
+	},
+	{ "reset", G_FLAG_VERBOSE, NULL, G_NULL_OPTS,
+	    "[-v] name ..."
+	},
+	{ "stop", G_FLAG_VERBOSE, NULL,
+	    {
+		{ 'f', "force", NULL, G_TYPE_NONE },
+		G_OPT_SENTINEL
+	    },
+	    "[-fv] name ..."
+	},
+	G_CMD_SENTINEL
+};
+
+static int verbose = 0;
+
+static void
+cache_main(struct gctl_req *req, unsigned flags)
+{
+	const char *name;
+
+	if ((flags & G_FLAG_VERBOSE) != 0)
+		verbose = 1;
+
+	name = gctl_get_ascii(req, "verb");
+	if (name == NULL) {
+		gctl_error(req, "No '%s' argument.", "verb");
+		return;
+	}
+	if (strcmp(name, "label") == 0)
+		cache_label(req);
+	else if (strcmp(name, "clear") == 0)
+		cache_clear(req);
+	else if (strcmp(name, "dump") == 0)
+		cache_dump(req);
+	else
+		gctl_error(req, "Unknown command: %s.", name);
+}
+
+static void
+cache_label(struct gctl_req *req)
+{
+	struct g_cache_metadata md;
+	u_char sector[512];
+	const char *name;
+	int error, nargs;
+	intmax_t val;
+
+	nargs = gctl_get_int(req, "nargs");
+	if (nargs != 2) {
+		gctl_error(req, "Invalid number of arguments.");
+		return;
+	}
+
+	strlcpy(md.md_magic, G_CACHE_MAGIC, sizeof(md.md_magic));
+	md.md_version = G_CACHE_VERSION;
+	name = gctl_get_ascii(req, "arg0");
+	strlcpy(md.md_name, name, sizeof(md.md_name));
+	val = gctl_get_intmax(req, "blocksize");
+	md.md_bsize = val;
+	val = gctl_get_intmax(req, "size");
+	md.md_size = val;
+
+	name = gctl_get_ascii(req, "arg1");
+	md.md_provsize = g_get_mediasize(name);
+	if (md.md_provsize == 0) {
+		fprintf(stderr, "Can't get mediasize of %s: %s.\n",
+		    name, strerror(errno));
+		gctl_error(req, "Not fully done.");
+		return;
+	}
+	cache_metadata_encode(&md, sector);
+	error = g_metadata_store(name, sector, sizeof(sector));
+	if (error != 0) {
+		fprintf(stderr, "Can't store metadata on %s: %s.\n",
+		    name, strerror(error));
+		gctl_error(req, "Not fully done.");
+		return;
+	}
+	if (verbose)
+		printf("Metadata value stored on %s.\n", name);
+}
+
+static void
+cache_clear(struct gctl_req *req)
+{
+	const char *name;
+	int error, i, nargs;
+
+	nargs = gctl_get_int(req, "nargs");
+	if (nargs < 1) {
+		gctl_error(req, "Too few arguments.");
+		return;
+	}
+
+	for (i = 0; i < nargs; i++) {
+		name = gctl_get_ascii(req, "arg%d", i);
+		error = g_metadata_clear(name, G_CACHE_MAGIC);
+		if (error != 0) {
+			fprintf(stderr, "Can't clear metadata on %s: %s.\n",
+			    name, strerror(error));
+			gctl_error(req, "Not fully done.");
+			continue;
+		}
+		if (verbose)
+			printf("Metadata cleared on %s.\n", name);
+	}
+}
+
+static void
+cache_metadata_dump(const struct g_cache_metadata *md)
+{
+
+	printf("         Magic string: %s\n", md->md_magic);
+	printf("     Metadata version: %u\n", (u_int)md->md_version);
+	printf("          Device name: %s\n", md->md_name);
+	printf("           Block size: %u\n", (u_int)md->md_bsize);
+	printf("           Cache size: %u\n", (u_int)md->md_size);
+	printf("        Provider size: %ju\n", (uintmax_t)md->md_provsize);
+}
+
+static void
+cache_dump(struct gctl_req *req)
+{
+	struct g_cache_metadata md, tmpmd;
+	const char *name;
+	int error, i, nargs;
+
+	nargs = gctl_get_int(req, "nargs");
+	if (nargs < 1) {
+		gctl_error(req, "Too few arguments.");
+		return;
+	}
+
+	for (i = 0; i < nargs; i++) {
+		name = gctl_get_ascii(req, "arg%d", i);
+		error = g_metadata_read(name, (u_char *)&tmpmd, sizeof(tmpmd),
+		    G_CACHE_MAGIC);
+		if (error != 0) {
+			fprintf(stderr, "Can't read metadata from %s: %s.\n",
+			    name, strerror(error));
+			gctl_error(req, "Not fully done.");
+			continue;
+		}
+		cache_metadata_decode((u_char *)&tmpmd, &md);
+		printf("Metadata on %s:\n", name);
+		cache_metadata_dump(&md);
+		printf("\n");
+	}
+}