Attachment 226841 Details for Bug 277271 – Patch that speeds up mkblkdevs on my (running) desktop from 19.5 down to 4 minutes

[patch] Patch that speeds up mkblkdevs on my (running) desktop from 19.5 down to 4 minutes

mkinitrd-devtree-cache-slaves.patch (text/plain), 4.17 KB, created by Alexandre Oliva on 2007-10-15 02:04:29 UTC

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Creator: Alexandre Oliva

Created: 2007-10-15 02:04:29 UTC

Size: 4.17 KB

patch

obsolete

>Index: nash/devtree.c
>===================================================================
>--- nash/devtree.c.orig	2007-10-14 22:37:10.000000000 -0200
>+++ nash/devtree.c	2007-10-14 23:56:03.000000000 -0200
>@@ -1125,6 +1125,23 @@ static const struct devtree_constraint {
>     { DEV_TYPE_NONE, DEV_TYPE_NONE, 0, 0 }
> };
> 
>+struct nash_slave_list {
>+    const char *name;
>+    int valid;
>+    dev_t devno;
>+    struct nash_slave_list *next;
>+};
>+
>+/* Setting this to zero rather than one ups the mkblkdevs time on a
>+ * certain box (*) from 4 minutes to 5.2 minutes (nearly zero system
>+ * time), compared with 19.5 minutes without any caching whatsoever
>+ * (more than 2/3rd of which on system CPU use).
>+ *
>+ * (*) 4 disks, 15 partitions each, combined in RAID 1 pairs, almost
>+ * all of which used as physical volumes of a single volume group
>+ * containing 6 logical volumes.  */
>+#define CACHE_SLAVES_ONCE 1
>+
> static int is_sysfs_slave(struct nash_dev_node *adult,
>     struct nash_dev_node *child)
> {
>@@ -1133,43 +1150,91 @@ static int is_sysfs_slave(struct nash_de
>     struct stat sb;
>     int rc = 0;
>     char slaves[strlen(child->bdev->sysfs_path) + strlen("/slaves") + 1];
>+    struct nash_slave_list **slavepp = &child->slave_cache, *slavep;
>+
>+#if CACHE_SLAVES_ONCE
>+    if (*slavepp == (void*)-1)
>+	return 0;
>+#endif
>+
>+    for (slavep = *slavepp; slavep; slavep = slavep->next)
>+	if (slavep->valid && slavep->devno == adult->bdev->devno)
>+	    return 1;
>+
>+#if CACHE_SLAVES_ONCE
>+    if (*slavepp)
>+	return 0;
>+#endif
> 
>     strcpy(slaves, child->bdev->sysfs_path);
>     strcat(slaves, "/slaves");
> 
>-    if (!(dir = opendir(slaves)))
>+    if (!(dir = opendir(slaves))) {
>+#if CACHE_SLAVES_ONCE
>+	child->slave_cache = (void*)-1;
>+#endif
>         return 0;
>+    }
> 
>     while ((entry = readdir(dir))) {
>-        char slave[strlen(slaves) + 1 + strlen(entry->d_name) + 1];
>-        char devpath[sizeof(slave) + strlen("/dev") + 1];
>-        char devbuf[32] = "";
>-        int maj, min;
>-        FILE *df;
>-
>-        strcpy(slave, slaves); 
>-        strcat(slave, "/");
>-        strcat(slave, entry->d_name);
>-        strcpy(devpath, slave);
>-        strcat(devpath, "/dev");
>+	dev_t devno;
> 
>-        lstat(slave, &sb);
>-        if (!S_ISLNK(sb.st_mode))
>-            continue;
>-
>-        if (!(df = fopen(devpath, "r")))
>-            continue;
>-
>-        if (!fgets(devbuf, 31, df)) {
>-            fclose(df);
>-            continue;
>-        }
>-        fclose(df);
>-
>-        if (sscanf(devbuf, "%d:%d", &maj, &min) != 2)
>-            continue;
>+	while (*slavepp &&
>+	       strcmp(entry->d_name, (slavep = *slavepp)->name) != 0) {
>+	    *slavepp = slavep->next;
>+	    free(slavep);
>+	}
>+
>+	if (!*slavepp) {
>+	    char slave[strlen(slaves) + 1 + strlen(entry->d_name) + 1];
>+	    char devpath[sizeof(slave) + strlen("/dev") + 1];
>+	    char devbuf[32] = "";
>+	    int maj, min;
>+	    FILE *df;
>+
>+	    *slavepp = slavep = calloc (1, sizeof (*slavep));
>+	    if (slavep) {
>+		slavep->name = strdup(entry->d_name);
>+		slavep->next = NULL;
>+		slavep->valid = 0;
>+		slavepp = &slavep->next;
>+	    }
>+
>+	    strcpy(slave, slaves);
>+	    strcat(slave, "/");
>+	    strcat(slave, entry->d_name);
>+	    strcpy(devpath, slave);
>+	    strcat(devpath, "/dev");
>+
>+	    lstat(slave, &sb);
>+	    if (!S_ISLNK(sb.st_mode))
>+		continue;
>+
>+	    if (!(df = fopen(devpath, "r")))
>+		continue;
>+
>+	    if (!fgets(devbuf, 31, df)) {
>+		fclose(df);
>+		continue;
>+	    }
>+	    fclose(df);
>+
>+	    if (sscanf(devbuf, "%d:%d", &maj, &min) != 2)
>+		continue;
>+
>+	    devno = makedev(maj,min);
>+	    if (slavep) {
>+		slavep->valid = 1;
>+		slavep->devno = devno;
>+	    }
>+	} else {
>+	    slavepp = &slavep->next;
>+	    if (!slavep->valid)
>+		continue;
>+	    devno = slavep->devno;
>+	}
> 
>-        if (makedev(maj,min) == adult->bdev->devno) {
>+	if (devno == adult->bdev->devno) {
>             rc = 1;
>             break;
>         }
>Index: nash/devtree.h
>===================================================================
>--- nash/devtree.h.orig	2007-09-21 05:03:03.000000000 -0300
>+++ nash/devtree.h	2007-10-14 22:39:37.000000000 -0200
>@@ -53,6 +53,8 @@ struct nash_dev_node {
> 
>     struct nash_dev_tree *tree;
> 
>+    struct nash_slave_list *slave_cache;
>+
>     int probe_mask;
> };
>

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Attachments on bug 277271: 226841