On Friday 01 October 2010 23:52:56 Nathan Fontenot wrote:
> This set of patches decouples the concept that a single memory
> section corresponds to a single directory in
> /sys/devices/system/memory/. On systems
> with large amounts of memory (1+ TB) there are performance issues
> related to creating the large number of sysfs directories. For
> a powerpc machine with 1 TB of memory we are creating 63,000+
> directories. This is resulting in boot times of around 45-50
> minutes for systems with 1 TB of memory and 8 hours for systems
> with 2 TB of memory. With this patch set applied I am now seeing
> boot times of 5 minutes or less.
>
> The root of this issue is in sysfs directory creation. Every time
> a directory is created a string compare is done against all sibling
> directories to ensure we do not create duplicates. The list of
> directory nodes in sysfs is kept as an unsorted list which results
> in this being an exponentially longer operation as the number of
> directories are created.
>
Can we simply remove this check for this case alone?! :)
Thanks
Nikanth
Do not check for an entry with the same name is already present, when
__sysfs_add_one() is directly called, bypassing sysfs_add_one().
Currently register_mem_sect_under_node() calls
sysfs_create_link_nowarn(), which is the only caller to do so.
Signed-off-by: Nikanth Karthikesan <knika...@suse.de>
---
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 7e54bac..14d965c 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -368,21 +368,16 @@ void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
* This function should be called between calls to
* sysfs_addrm_start() and sysfs_addrm_finish() and should be
* passed the same @acxt as passed to sysfs_addrm_start().
+ * And there should be no sibling with the same name.
*
* LOCKING:
* Determined by sysfs_addrm_start().
*
- * RETURNS:
- * 0 on success, -EEXIST if entry with the given name already
- * exists.
*/
-int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
+void __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
{
struct sysfs_inode_attrs *ps_iattr;
- if (sysfs_find_dirent(acxt->parent_sd, sd->s_ns, sd->s_name))
- return -EEXIST;
-
sd->s_parent = sysfs_get(acxt->parent_sd);
sysfs_link_sibling(sd);
@@ -394,7 +389,6 @@ int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct
sysfs_dirent *sd)
ps_iattrs->ia_ctime = ps_iattrs->ia_mtime = CURRENT_TIME;
}
- return 0;
}
/**
@@ -439,10 +433,9 @@ static char *sysfs_pathname(struct sysfs_dirent *sd, char
*path)
*/
int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd)
{
- int ret;
+ int ret = 0;
- ret = __sysfs_add_one(acxt, sd);
- if (ret == -EEXIST) {
+ if (sysfs_find_dirent(acxt->parent_sd, sd->s_ns, sd->s_name)) {
char *path = kzalloc(PATH_MAX, GFP_KERNEL);
WARN(1, KERN_WARNING
"sysfs: cannot create duplicate filename '%s'\n",
@@ -450,8 +443,11 @@ int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct
sysfs_dirent *sd)
strcat(strcat(sysfs_pathname(acxt->parent_sd, path), "/"),
sd->s_name));
kfree(path);
+ ret = -EEXIST;
}
+ __sysfs_add_one(acxt, sd);
+
return ret;
}
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index a7ac78f..7c56d34 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -72,7 +72,7 @@ static int sysfs_do_create_link(struct kobject *kobj, struct
kobject *target,
if (warn)
error = sysfs_add_one(&acxt, sd);
else
- error = __sysfs_add_one(&acxt, sd);
+ __sysfs_add_one(&acxt, sd);
} else {
error = -EINVAL;
WARN(1, KERN_WARNING
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index d9be60a..35449c8 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -155,7 +155,7 @@ struct sysfs_dirent *sysfs_get_active(struct sysfs_dirent
*sd);
void sysfs_put_active(struct sysfs_dirent *sd);
void sysfs_addrm_start(struct sysfs_addrm_cxt *acxt,
struct sysfs_dirent *parent_sd);
-int __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
+void __sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
int sysfs_add_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
void sysfs_remove_one(struct sysfs_addrm_cxt *acxt, struct sysfs_dirent *sd);
void sysfs_addrm_finish(struct sysfs_addrm_cxt *acxt);
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