From: Miklos Szeredi <miklos@szeredi.hu>
To: sedat.dilek@gmail.com
Cc: viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, hch@infradead.org,
torvalds@linux-foundation.org, akpm@linux-foundation.org,
apw@canonical.com, nbd@openwrt.org, neilb@suse.de,
jordipujolp@gmail.com, ezk@fsl.cs.sunysb.edu,
ricwheeler@gmail.com, dhowells@redhat.com, hpj@urpla.net,
sedat.dilek@googlemail.com, penberg@kernel.org,
goran.cetusic@gmail.com, romain@orebokech.com
Subject: Re: [PATCH 08/13] fs: limit filesystem stacking depth
Date: Mon, 03 Sep 2012 17:05:55 +0200 [thread overview]
Message-ID: <87mx17du3w.fsf@tucsk.pomaz.szeredi.hu> (raw)
In-Reply-To: <CA+icZUVz1DNBipOOT_j+ewKSuuFR0775RKyRWq4CcDqwafqC8Q@mail.gmail.com> (Sedat Dilek's message of "Thu, 16 Aug 2012 15:24:08 +0200")
Sedat Dilek <sedat.dilek@gmail.com> writes:
>>
>> Yes, setting it to 2 is defensive, it would need more stack depth
>> analysis to see what an acceptable number would be.
>>
>
> Can you describe such an analysis method (in case you need help for
> testing it)?
I attached a systemtap script (x86-64 specific) which prints stack use
for stacked overlayfs filesystems. Interpret output like this:
7288 0 ovl_lookup (bash/5721)
^ ^
| |
| +- function name (process/pid)
|
+------------ current stack use
7080 208 ovl_permission (bash/5721)
^ ^
| |
| +- stacking depth indicated by indentation
|
+------ stack increase from previous stacking level
You can try it on various setups (overlayfs being used as the lower
and/or upper level) and executing various filesystem operations.
Looks like "copy up" is the most stack hungry operation, it may be worth
trying to reduce its stack usage.
Thanks,
Miklos
---
global rec_level, stacks
probe
kernel.function("ovl_permission"),
kernel.function("ovl_getattr"),
kernel.function("ovl_dir_getattr"),
kernel.function("ovl_setattr"),
kernel.function("ovl_setxattr"),
kernel.function("ovl_listxattr"),
kernel.function("ovl_removexattr"),
kernel.function("ovl_dentry_open"),
kernel.function("ovl_lookup"),
kernel.function("ovl_mkdir"),
kernel.function("ovl_symlink"),
kernel.function("ovl_unlink"),
kernel.function("ovl_rmdir"),
kernel.function("ovl_rename"),
kernel.function("ovl_link"),
kernel.function("ovl_create"),
kernel.function("ovl_mknod"),
kernel.function("ovl_follow_link"),
kernel.function("ovl_put_link"),
kernel.function("ovl_readlink"),
kernel.function("ovl_dir_open"),
kernel.function("ovl_readdir"),
kernel.function("ovl_dir_llseek"),
kernel.function("ovl_dir_fsync"),
kernel.function("ovl_dir_release"),
kernel.function("ovl_dentry_release"),
kernel.function("ovl_put_super"),
kernel.function("ovl_statfs")
{
tid = tid();
i = rec_level[tid]++;
stack_rem = u_register("rbp") & 0x1fff;
stacks[tid, i] = stack_rem;
delta = i > 0 ? stacks[tid, i - 1] - stack_rem : 0;
printf("%4i %4i %-*s %s (%s/%i)\n", stack_rem, delta, i * 8, "", probefunc(), execname(), tid);
}
probe
kernel.function("ovl_permission").return,
kernel.function("ovl_getattr").return,
kernel.function("ovl_dir_getattr").return,
kernel.function("ovl_setattr").return,
kernel.function("ovl_setxattr").return,
kernel.function("ovl_listxattr").return,
kernel.function("ovl_removexattr").return,
kernel.function("ovl_dentry_open").return,
kernel.function("ovl_lookup").return,
kernel.function("ovl_mkdir").return,
kernel.function("ovl_symlink").return,
kernel.function("ovl_unlink").return,
kernel.function("ovl_rmdir").return,
kernel.function("ovl_rename").return,
kernel.function("ovl_link").return,
kernel.function("ovl_create").return,
kernel.function("ovl_mknod").return,
kernel.function("ovl_follow_link").return,
kernel.function("ovl_put_link").return,
kernel.function("ovl_readlink").return,
kernel.function("ovl_dir_open").return,
kernel.function("ovl_readdir").return,
kernel.function("ovl_dir_llseek").return,
kernel.function("ovl_dir_fsync").return,
kernel.function("ovl_dir_release").return,
kernel.function("ovl_dentry_release").return,
kernel.function("ovl_put_super").return,
kernel.function("ovl_statfs").return
{
rec_level[tid()]--;
}
next prev parent reply other threads:[~2012-09-03 15:04 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-15 15:48 [PATCH 00/13] overlay filesystem: request for inclusion (v14) Miklos Szeredi
2012-08-15 15:48 ` [PATCH 01/13] vfs: add i_op->open() Miklos Szeredi
2012-08-15 17:21 ` J. Bruce Fields
2012-08-15 20:28 ` NeilBrown
2012-08-16 10:10 ` Miklos Szeredi
2012-08-15 15:48 ` [PATCH 02/13] vfs: export do_splice_direct() to modules Miklos Szeredi
2012-08-15 15:48 ` [PATCH 03/13] vfs: introduce clone_private_mount() Miklos Szeredi
2012-08-15 15:48 ` [PATCH 04/13] overlay filesystem Miklos Szeredi
2012-08-16 6:24 ` Eric W. Biederman
2012-08-16 10:25 ` Miklos Szeredi
2012-08-15 15:48 ` [PATCH 05/13] overlayfs: add statfs support Miklos Szeredi
2012-08-17 18:20 ` Ben Hutchings
2012-08-29 22:48 ` Miklos Szeredi
2012-08-30 5:54 ` Ben Hutchings
2012-08-31 12:47 ` J. R. Okajima
2012-08-15 15:48 ` [PATCH 06/13] overlayfs: implement show_options Miklos Szeredi
2012-08-15 15:48 ` [PATCH 07/13] overlay: overlay filesystem documentation Miklos Szeredi
2012-08-15 19:53 ` J. Bruce Fields
2012-08-16 10:09 ` Miklos Szeredi
2012-09-10 1:47 ` Jan Engelhardt
2012-09-10 3:18 ` NeilBrown
2012-08-15 15:48 ` [PATCH 08/13] fs: limit filesystem stacking depth Miklos Szeredi
2012-08-16 8:02 ` Sedat Dilek
2012-08-16 8:30 ` Sedat Dilek
2012-08-16 10:42 ` Miklos Szeredi
2012-08-16 13:24 ` Sedat Dilek
2012-09-03 15:05 ` Miklos Szeredi [this message]
2012-08-15 15:48 ` [PATCH 09/13] overlayfs: fix possible leak in ovl_new_inode Miklos Szeredi
2012-08-15 15:48 ` [PATCH 10/13] overlayfs: create new inode in ovl_link Miklos Szeredi
2012-08-15 15:48 ` [PATCH 11/13] vfs: export __inode_permission() to modules Miklos Szeredi
2012-08-15 17:17 ` Sedat Dilek
2012-08-15 15:48 ` [PATCH 12/13] ovl: switch to __inode_permission() Miklos Szeredi
2012-08-15 16:59 ` Casey Schaufler
2012-08-15 17:07 ` Andy Whitcroft
2012-08-15 17:34 ` Casey Schaufler
2012-08-15 15:48 ` [PATCH 13/13] overlayfs: copy up i_uid/i_gid from the underlying inode Miklos Szeredi
2012-08-15 17:14 ` [PATCH 00/13] overlay filesystem: request for inclusion (v14) Sedat Dilek
2012-09-20 18:55 [PATCH 00/13] overlay filesystem: request for inclusion (v15) Miklos Szeredi
2012-09-20 18:55 ` [PATCH 08/13] fs: limit filesystem stacking depth Miklos Szeredi
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