* [PATCH v3] inotify: Increase default inotify.max_user_watches limit to 1048576
@ 2020-10-29 19:42 Waiman Long
2020-10-30 10:57 ` Jan Kara
0 siblings, 1 reply; 3+ messages in thread
From: Waiman Long @ 2020-10-29 19:42 UTC (permalink / raw)
To: Jan Kara, Amir Goldstein
Cc: linux-fsdevel, linux-kernel, Luca BRUNO, Waiman Long
The default value of inotify.max_user_watches sysctl parameter was set
to 8192 since the introduction of the inotify feature in 2005 by
commit 0eeca28300df ("[PATCH] inotify"). Today this value is just too
small for many modern usage. As a result, users have to explicitly set
it to a larger value to make it work.
After some searching around the web, these are the
inotify.max_user_watches values used by some projects:
- vscode: 524288
- dropbox support: 100000
- users on stackexchange: 12228
- lsyncd user: 2000000
- code42 support: 1048576
- monodevelop: 16384
- tectonic: 524288
- openshift origin: 65536
Each watch point adds an inotify_inode_mark structure to an inode to
be watched. It also pins the watched inode.
Modeled after the epoll.max_user_watches behavior to adjust the default
value according to the amount of addressable memory available, make
inotify.max_user_watches behave in a similar way to make it use no more
than 1% of addressable memory within the range [8192, 1048576].
For 64-bit archs, inotify_inode_mark plus 2 vfs inode have a size that
is a bit over 1 kbytes (1284 bytes with my x86-64 config). That means
a system with 128GB or more memory will likely have the maximum value
of 1048576 for inotify.max_user_watches. This default should be big
enough for most use cases.
[v3: increase inotify watch cost as suggested by Amir and Honza]
Signed-off-by: Waiman Long <longman@redhat.com>
---
fs/notify/inotify/inotify_user.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 186722ba3894..f8065eda3a02 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -37,6 +37,15 @@
#include <asm/ioctls.h>
+/*
+ * An inotify watch requires allocating an inotify_inode_mark structure as
+ * well as pinning the watched inode. Doubling the size of a VFS inode
+ * should be more than enough to cover the additional filesystem inode
+ * size increase.
+ */
+#define INOTIFY_WATCH_COST (sizeof(struct inotify_inode_mark) + \
+ 2 * sizeof(struct inode))
+
/* configurable via /proc/sys/fs/inotify/ */
static int inotify_max_queued_events __read_mostly;
@@ -801,6 +810,18 @@ SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
*/
static int __init inotify_user_setup(void)
{
+ unsigned int watches_max;
+ struct sysinfo si;
+
+ si_meminfo(&si);
+ /*
+ * Allow up to 1% of addressible memory to be allocated for inotify
+ * watches (per user) limited to the range [8192, 1048576].
+ */
+ watches_max = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
+ INOTIFY_WATCH_COST;
+ watches_max = min(1048576U, max(watches_max, 8192U));
+
BUILD_BUG_ON(IN_ACCESS != FS_ACCESS);
BUILD_BUG_ON(IN_MODIFY != FS_MODIFY);
BUILD_BUG_ON(IN_ATTRIB != FS_ATTRIB);
@@ -827,7 +848,7 @@ static int __init inotify_user_setup(void)
inotify_max_queued_events = 16384;
init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
- init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = 8192;
+ init_user_ns.ucount_max[UCOUNT_INOTIFY_WATCHES] = watches_max;
return 0;
}
--
2.18.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] inotify: Increase default inotify.max_user_watches limit to 1048576
2020-10-29 19:42 [PATCH v3] inotify: Increase default inotify.max_user_watches limit to 1048576 Waiman Long
@ 2020-10-30 10:57 ` Jan Kara
2020-11-09 2:17 ` Waiman Long
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kara @ 2020-10-30 10:57 UTC (permalink / raw)
To: Waiman Long
Cc: Jan Kara, Amir Goldstein, linux-fsdevel, linux-kernel, Luca BRUNO
On Thu 29-10-20 15:42:56, Waiman Long wrote:
> The default value of inotify.max_user_watches sysctl parameter was set
> to 8192 since the introduction of the inotify feature in 2005 by
> commit 0eeca28300df ("[PATCH] inotify"). Today this value is just too
> small for many modern usage. As a result, users have to explicitly set
> it to a larger value to make it work.
>
> After some searching around the web, these are the
> inotify.max_user_watches values used by some projects:
> - vscode: 524288
> - dropbox support: 100000
> - users on stackexchange: 12228
> - lsyncd user: 2000000
> - code42 support: 1048576
> - monodevelop: 16384
> - tectonic: 524288
> - openshift origin: 65536
>
> Each watch point adds an inotify_inode_mark structure to an inode to
> be watched. It also pins the watched inode.
>
> Modeled after the epoll.max_user_watches behavior to adjust the default
> value according to the amount of addressable memory available, make
> inotify.max_user_watches behave in a similar way to make it use no more
> than 1% of addressable memory within the range [8192, 1048576].
>
> For 64-bit archs, inotify_inode_mark plus 2 vfs inode have a size that
> is a bit over 1 kbytes (1284 bytes with my x86-64 config). That means
> a system with 128GB or more memory will likely have the maximum value
> of 1048576 for inotify.max_user_watches. This default should be big
> enough for most use cases.
>
> [v3: increase inotify watch cost as suggested by Amir and Honza]
>
> Signed-off-by: Waiman Long <longman@redhat.com>
Overall this looks fine. Some remaining nits below.
> diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
> index 186722ba3894..f8065eda3a02 100644
> --- a/fs/notify/inotify/inotify_user.c
> +++ b/fs/notify/inotify/inotify_user.c
> @@ -37,6 +37,15 @@
>
> #include <asm/ioctls.h>
>
> +/*
> + * An inotify watch requires allocating an inotify_inode_mark structure as
> + * well as pinning the watched inode. Doubling the size of a VFS inode
> + * should be more than enough to cover the additional filesystem inode
> + * size increase.
> + */
> +#define INOTIFY_WATCH_COST (sizeof(struct inotify_inode_mark) + \
> + 2 * sizeof(struct inode))
> +
> /* configurable via /proc/sys/fs/inotify/ */
> static int inotify_max_queued_events __read_mostly;
>
> @@ -801,6 +810,18 @@ SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
> */
> static int __init inotify_user_setup(void)
> {
> + unsigned int watches_max;
> + struct sysinfo si;
> +
> + si_meminfo(&si);
> + /*
> + * Allow up to 1% of addressible memory to be allocated for inotify
^^^^ addressable
> + * watches (per user) limited to the range [8192, 1048576].
> + */
> + watches_max = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
> + INOTIFY_WATCH_COST;
^^^ So for machines with > 1TB of memory
watches_max would overflow. So you probably need to use ulong for that.
> + watches_max = min(1048576U, max(watches_max, 8192U));
^^^ use clamp() here?
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] inotify: Increase default inotify.max_user_watches limit to 1048576
2020-10-30 10:57 ` Jan Kara
@ 2020-11-09 2:17 ` Waiman Long
0 siblings, 0 replies; 3+ messages in thread
From: Waiman Long @ 2020-11-09 2:17 UTC (permalink / raw)
To: Jan Kara; +Cc: Amir Goldstein, linux-fsdevel, linux-kernel, Luca BRUNO
On 10/30/20 6:57 AM, Jan Kara wrote:
> On Thu 29-10-20 15:42:56, Waiman Long wrote:
>> The default value of inotify.max_user_watches sysctl parameter was set
>> to 8192 since the introduction of the inotify feature in 2005 by
>> commit 0eeca28300df ("[PATCH] inotify"). Today this value is just too
>> small for many modern usage. As a result, users have to explicitly set
>> it to a larger value to make it work.
>>
>> After some searching around the web, these are the
>> inotify.max_user_watches values used by some projects:
>> - vscode: 524288
>> - dropbox support: 100000
>> - users on stackexchange: 12228
>> - lsyncd user: 2000000
>> - code42 support: 1048576
>> - monodevelop: 16384
>> - tectonic: 524288
>> - openshift origin: 65536
>>
>> Each watch point adds an inotify_inode_mark structure to an inode to
>> be watched. It also pins the watched inode.
>>
>> Modeled after the epoll.max_user_watches behavior to adjust the default
>> value according to the amount of addressable memory available, make
>> inotify.max_user_watches behave in a similar way to make it use no more
>> than 1% of addressable memory within the range [8192, 1048576].
>>
>> For 64-bit archs, inotify_inode_mark plus 2 vfs inode have a size that
>> is a bit over 1 kbytes (1284 bytes with my x86-64 config). That means
>> a system with 128GB or more memory will likely have the maximum value
>> of 1048576 for inotify.max_user_watches. This default should be big
>> enough for most use cases.
>>
>> [v3: increase inotify watch cost as suggested by Amir and Honza]
>>
>> Signed-off-by: Waiman Long <longman@redhat.com>
> Overall this looks fine. Some remaining nits below.
>
>> diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
>> index 186722ba3894..f8065eda3a02 100644
>> --- a/fs/notify/inotify/inotify_user.c
>> +++ b/fs/notify/inotify/inotify_user.c
>> @@ -37,6 +37,15 @@
>>
>> #include <asm/ioctls.h>
>>
>> +/*
>> + * An inotify watch requires allocating an inotify_inode_mark structure as
>> + * well as pinning the watched inode. Doubling the size of a VFS inode
>> + * should be more than enough to cover the additional filesystem inode
>> + * size increase.
>> + */
>> +#define INOTIFY_WATCH_COST (sizeof(struct inotify_inode_mark) + \
>> + 2 * sizeof(struct inode))
>> +
>> /* configurable via /proc/sys/fs/inotify/ */
>> static int inotify_max_queued_events __read_mostly;
>>
>> @@ -801,6 +810,18 @@ SYSCALL_DEFINE2(inotify_rm_watch, int, fd, __s32, wd)
>> */
>> static int __init inotify_user_setup(void)
>> {
>> + unsigned int watches_max;
>> + struct sysinfo si;
>> +
>> + si_meminfo(&si);
>> + /*
>> + * Allow up to 1% of addressible memory to be allocated for inotify
> ^^^^ addressable
>
>> + * watches (per user) limited to the range [8192, 1048576].
>> + */
>> + watches_max = (((si.totalram - si.totalhigh) / 100) << PAGE_SHIFT) /
>> + INOTIFY_WATCH_COST;
> ^^^ So for machines with > 1TB of memory
> watches_max would overflow. So you probably need to use ulong for that.
>
>
>> + watches_max = min(1048576U, max(watches_max, 8192U));
> ^^^ use clamp() here?
Yes, it will be easier to read to use clamp() here. Will send out v4
withat those changes.
Thanks,
Longman
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-11-09 2:17 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-29 19:42 [PATCH v3] inotify: Increase default inotify.max_user_watches limit to 1048576 Waiman Long
2020-10-30 10:57 ` Jan Kara
2020-11-09 2:17 ` Waiman Long
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.