Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-21 Thread Ian Kent
On Sat, 2020-12-19 at 15:47 +0800, Fox Chen wrote: > On Sat, Dec 19, 2020 at 8:53 AM Ian Kent wrote: > > On Fri, 2020-12-18 at 21:20 +0800, Fox Chen wrote: > > > On Fri, Dec 18, 2020 at 7:21 PM Ian Kent > > > wrote: > > > > On Fri, 2020-12-18 at 16:01 +0800, Fox Chen wrote: > > > > > On Fri, Dec

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-21 Thread Fox Chen
On Sun, Dec 20, 2020 at 7:52 AM Ian Kent wrote: > > On Sat, 2020-12-19 at 11:23 -0500, Tejun Heo wrote: > > Hello, > > > > On Sat, Dec 19, 2020 at 03:08:13PM +0800, Ian Kent wrote: > > > And looking further I see there's a race that kernfs can't do > > > anything > > > about between

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-19 Thread Ian Kent
On Sun, 2020-12-20 at 07:52 +0800, Ian Kent wrote: > On Sat, 2020-12-19 at 11:23 -0500, Tejun Heo wrote: > > Hello, > > > > On Sat, Dec 19, 2020 at 03:08:13PM +0800, Ian Kent wrote: > > > And looking further I see there's a race that kernfs can't do > > > anything > > > about between

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-19 Thread Ian Kent
On Sat, 2020-12-19 at 11:23 -0500, Tejun Heo wrote: > Hello, > > On Sat, Dec 19, 2020 at 03:08:13PM +0800, Ian Kent wrote: > > And looking further I see there's a race that kernfs can't do > > anything > > about between kernfs_refresh_inode() and fs/inode.c:update_times(). > > Do kernfs files

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-19 Thread Tejun Heo
Hello, On Sat, Dec 19, 2020 at 03:08:13PM +0800, Ian Kent wrote: > And looking further I see there's a race that kernfs can't do anything > about between kernfs_refresh_inode() and fs/inode.c:update_times(). Do kernfs files end up calling into that path tho? Doesn't look like it to me but if so

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Fox Chen
On Sat, Dec 19, 2020 at 8:53 AM Ian Kent wrote: > > On Fri, 2020-12-18 at 21:20 +0800, Fox Chen wrote: > > On Fri, Dec 18, 2020 at 7:21 PM Ian Kent wrote: > > > On Fri, 2020-12-18 at 16:01 +0800, Fox Chen wrote: > > > > On Fri, Dec 18, 2020 at 3:36 PM Ian Kent > > > > wrote: > > > > > On Thu,

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Ian Kent
On Fri, 2020-12-18 at 09:59 -0500, Tejun Heo wrote: > Hello, > > On Fri, Dec 18, 2020 at 03:36:21PM +0800, Ian Kent wrote: > > Sounds like your saying it would be ok to add a lock to the > > attrs structure, am I correct? > > Yeah, adding a lock to attrs is a lot less of a problem and it looks >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Ian Kent
On Fri, 2020-12-18 at 21:20 +0800, Fox Chen wrote: > On Fri, Dec 18, 2020 at 7:21 PM Ian Kent wrote: > > On Fri, 2020-12-18 at 16:01 +0800, Fox Chen wrote: > > > On Fri, Dec 18, 2020 at 3:36 PM Ian Kent > > > wrote: > > > > On Thu, 2020-12-17 at 10:14 -0500, Tejun Heo wrote: > > > > > Hello, > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Tejun Heo
Hello, On Fri, Dec 18, 2020 at 03:36:21PM +0800, Ian Kent wrote: > Sounds like your saying it would be ok to add a lock to the > attrs structure, am I correct? Yeah, adding a lock to attrs is a lot less of a problem and it looks like it's gonna have to be either that or hashed locks, which might

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Fox Chen
On Fri, Dec 18, 2020 at 7:21 PM Ian Kent wrote: > > On Fri, 2020-12-18 at 16:01 +0800, Fox Chen wrote: > > On Fri, Dec 18, 2020 at 3:36 PM Ian Kent wrote: > > > On Thu, 2020-12-17 at 10:14 -0500, Tejun Heo wrote: > > > > Hello, > > > > > > > > On Thu, Dec 17, 2020 at 07:48:49PM +0800, Ian Kent

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Ian Kent
On Fri, 2020-12-18 at 16:01 +0800, Fox Chen wrote: > On Fri, Dec 18, 2020 at 3:36 PM Ian Kent wrote: > > On Thu, 2020-12-17 at 10:14 -0500, Tejun Heo wrote: > > > Hello, > > > > > > On Thu, Dec 17, 2020 at 07:48:49PM +0800, Ian Kent wrote: > > > > > What could be done is to make the kernfs node

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-18 Thread Fox Chen
On Fri, Dec 18, 2020 at 3:36 PM Ian Kent wrote: > > On Thu, 2020-12-17 at 10:14 -0500, Tejun Heo wrote: > > Hello, > > > > On Thu, Dec 17, 2020 at 07:48:49PM +0800, Ian Kent wrote: > > > > What could be done is to make the kernfs node attr_mutex > > > > a pointer and dynamically allocate it but

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-17 Thread Ian Kent
On Thu, 2020-12-17 at 10:14 -0500, Tejun Heo wrote: > Hello, > > On Thu, Dec 17, 2020 at 07:48:49PM +0800, Ian Kent wrote: > > > What could be done is to make the kernfs node attr_mutex > > > a pointer and dynamically allocate it but even that is too > > > costly a size addition to the kernfs

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-17 Thread Tejun Heo
Hello, On Thu, Dec 17, 2020 at 07:48:49PM +0800, Ian Kent wrote: > > What could be done is to make the kernfs node attr_mutex > > a pointer and dynamically allocate it but even that is too > > costly a size addition to the kernfs node structure as > > Tejun has said. > > I guess the question to

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-17 Thread Ian Kent
On Thu, 2020-12-17 at 19:09 +0800, Ian Kent wrote: > On Thu, 2020-12-17 at 18:09 +0800, Ian Kent wrote: > > On Thu, 2020-12-17 at 16:54 +0800, Fox Chen wrote: > > > On Thu, Dec 17, 2020 at 12:46 PM Ian Kent > > > wrote: > > > > On Tue, 2020-12-15 at 20:59 +0800, Ian Kent wrote: > > > > > On Tue,

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-17 Thread Ian Kent
On Thu, 2020-12-17 at 18:09 +0800, Ian Kent wrote: > On Thu, 2020-12-17 at 16:54 +0800, Fox Chen wrote: > > On Thu, Dec 17, 2020 at 12:46 PM Ian Kent wrote: > > > On Tue, 2020-12-15 at 20:59 +0800, Ian Kent wrote: > > > > On Tue, 2020-12-15 at 16:33 +0800, Fox Chen wrote: > > > > > On Mon, Dec

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-17 Thread Ian Kent
On Thu, 2020-12-17 at 16:54 +0800, Fox Chen wrote: > On Thu, Dec 17, 2020 at 12:46 PM Ian Kent wrote: > > On Tue, 2020-12-15 at 20:59 +0800, Ian Kent wrote: > > > On Tue, 2020-12-15 at 16:33 +0800, Fox Chen wrote: > > > > On Mon, Dec 14, 2020 at 9:30 PM Ian Kent > > > > wrote: > > > > > On Mon,

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-17 Thread Fox Chen
On Thu, Dec 17, 2020 at 12:46 PM Ian Kent wrote: > > On Tue, 2020-12-15 at 20:59 +0800, Ian Kent wrote: > > On Tue, 2020-12-15 at 16:33 +0800, Fox Chen wrote: > > > On Mon, Dec 14, 2020 at 9:30 PM Ian Kent wrote: > > > > On Mon, 2020-12-14 at 14:14 +0800, Fox Chen wrote: > > > > > On Sun, Dec

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-16 Thread Ian Kent
On Tue, 2020-12-15 at 20:59 +0800, Ian Kent wrote: > On Tue, 2020-12-15 at 16:33 +0800, Fox Chen wrote: > > On Mon, Dec 14, 2020 at 9:30 PM Ian Kent wrote: > > > On Mon, 2020-12-14 at 14:14 +0800, Fox Chen wrote: > > > > On Sun, Dec 13, 2020 at 11:46 AM Ian Kent > > > > wrote: > > > > > On Fri,

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-15 Thread Ian Kent
On Tue, 2020-12-15 at 16:33 +0800, Fox Chen wrote: > On Mon, Dec 14, 2020 at 9:30 PM Ian Kent wrote: > > On Mon, 2020-12-14 at 14:14 +0800, Fox Chen wrote: > > > On Sun, Dec 13, 2020 at 11:46 AM Ian Kent > > > wrote: > > > > On Fri, 2020-12-11 at 10:17 +0800, Ian Kent wrote: > > > > > On Fri,

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-15 Thread Fox Chen
On Mon, Dec 14, 2020 at 9:30 PM Ian Kent wrote: > > On Mon, 2020-12-14 at 14:14 +0800, Fox Chen wrote: > > On Sun, Dec 13, 2020 at 11:46 AM Ian Kent wrote: > > > On Fri, 2020-12-11 at 10:17 +0800, Ian Kent wrote: > > > > On Fri, 2020-12-11 at 10:01 +0800, Ian Kent wrote: > > > > > > For the

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-14 Thread Ian Kent
On Mon, 2020-12-14 at 14:14 +0800, Fox Chen wrote: > On Sun, Dec 13, 2020 at 11:46 AM Ian Kent wrote: > > On Fri, 2020-12-11 at 10:17 +0800, Ian Kent wrote: > > > On Fri, 2020-12-11 at 10:01 +0800, Ian Kent wrote: > > > > > For the patches, there is a mutex_lock in kn->attr_mutex, as > > > > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-13 Thread Fox Chen
On Sun, Dec 13, 2020 at 11:46 AM Ian Kent wrote: > > On Fri, 2020-12-11 at 10:17 +0800, Ian Kent wrote: > > On Fri, 2020-12-11 at 10:01 +0800, Ian Kent wrote: > > > > For the patches, there is a mutex_lock in kn->attr_mutex, as > > > > Tejun > > > > mentioned here > > > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-12 Thread Ian Kent
On Fri, 2020-12-11 at 10:17 +0800, Ian Kent wrote: > On Fri, 2020-12-11 at 10:01 +0800, Ian Kent wrote: > > > For the patches, there is a mutex_lock in kn->attr_mutex, as > > > Tejun > > > mentioned here > > > (https://lore.kernel.org/lkml/x8fe0cmu+aq1g...@mtj.duckdns.org/), > > > maybe a global

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-10 Thread Ian Kent
On Fri, 2020-12-11 at 10:01 +0800, Ian Kent wrote: > > > For the patches, there is a mutex_lock in kn->attr_mutex, as Tejun > > mentioned here > > (https://lore.kernel.org/lkml/x8fe0cmu+aq1g...@mtj.duckdns.org/), > > maybe a global > > rwsem for kn->iattr will be better?? > > I wasn't sure

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-10 Thread Ian Kent
On Thu, 2020-12-10 at 16:44 +, Fox Chen wrote: > Hi, > > I found this series of patches solves exact the problem I am trying > to solve. > https://lore.kernel.org/lkml/20201202145837.48040-1-foxhlc...@gmail.com/ Right. > > The problem is reported by Brice Goglin on thread: > Re: [PATCH

RE:[PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-12-10 Thread Fox Chen
Hi, I found this series of patches solves exact the problem I am trying to solve. https://lore.kernel.org/lkml/20201202145837.48040-1-foxhlc...@gmail.com/ The problem is reported by Brice Goglin on thread: Re: [PATCH 1/4] drivers core: Introduce CPU type sysfs interface

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-25 Thread Ian Kent
On Thu, 2020-06-25 at 11:43 +0200, Greg Kroah-Hartman wrote: > On Thu, Jun 25, 2020 at 04:15:19PM +0800, Ian Kent wrote: > > On Tue, 2020-06-23 at 19:13 -0400, Tejun Heo wrote: > > > Hello, Rick. > > > > > > On Mon, Jun 22, 2020 at 02:22:34PM -0700, Rick Lindsley wrote: > > > > > I don't know.

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-25 Thread Greg Kroah-Hartman
On Thu, Jun 25, 2020 at 04:15:19PM +0800, Ian Kent wrote: > On Tue, 2020-06-23 at 19:13 -0400, Tejun Heo wrote: > > Hello, Rick. > > > > On Mon, Jun 22, 2020 at 02:22:34PM -0700, Rick Lindsley wrote: > > > > I don't know. The above highlights the absurdity of the approach > > > > itself to > > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-25 Thread Ian Kent
On Tue, 2020-06-23 at 19:13 -0400, Tejun Heo wrote: > Hello, Rick. > > On Mon, Jun 22, 2020 at 02:22:34PM -0700, Rick Lindsley wrote: > > > I don't know. The above highlights the absurdity of the approach > > > itself to > > > me. You seem to be aware of it too in writing: 250,000 "devices". > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-24 Thread Tejun Heo
Hello, Rick. On Wed, Jun 24, 2020 at 02:04:15AM -0700, Rick Lindsley wrote: > In contrast, the provided patch fixes the observed problem with no ripple > effect to other subsystems or utilities. > > Greg had suggested > Treat the system as a whole please, don't go for a short-term > fix

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-24 Thread Greg Kroah-Hartman
On Wed, Jun 24, 2020 at 02:04:15AM -0700, Rick Lindsley wrote: > In contrast, the provided patch fixes the observed problem with no ripple > effect to other subsystems or utilities. Your patch, as-is, is fine, but to somehow think that this is going to solve your real problem here is the issue we

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-24 Thread Rick Lindsley
Thanks, Tejun, appreciate the feedback. On 6/23/20 4:13 PM, Tejun Heo wrote: The problem is fitting that into an interface which wholly doesn't fit that particular requirement. It's not that difficult to imagine different ways to represent however many memory slots, right? Perhaps we have

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Tejun Heo
Hello, Rick. On Mon, Jun 22, 2020 at 02:22:34PM -0700, Rick Lindsley wrote: > > I don't know. The above highlights the absurdity of the approach itself to > > me. You seem to be aware of it too in writing: 250,000 "devices". > > Just because it is absurd doesn't mean it wasn't built that way :)

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Rick Lindsley
On 6/23/20 4:45 AM, Greg Kroah-Hartman wrote: Sure, but "help, I'm abusing your code interface, so fix your code interface and not my caller code" really isn't the best mantra :) Well, those are your words, not mine. What we're saying is, "we've identified an interface that doesn't scale in

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Ian Kent
On Tue, 2020-06-23 at 02:33 -0700, Rick Lindsley wrote: > On 6/22/20 11:02 PM, Greg Kroah-Hartman wrote: > > > First off, this is not my platform, and not my problem, so it's > > funny > > you ask me :) > > Wlll, not your platform perhaps but MAINTAINERS does list you > first and Tejun

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Greg Kroah-Hartman
On Tue, Jun 23, 2020 at 04:01:52PM +0800, Ian Kent wrote: > On Tue, 2020-06-23 at 08:02 +0200, Greg Kroah-Hartman wrote: > > On Tue, Jun 23, 2020 at 01:09:08PM +0800, Ian Kent wrote: > > > On Mon, 2020-06-22 at 20:03 +0200, Greg Kroah-Hartman wrote: > > > > On Mon, Jun 22, 2020 at 01:48:45PM

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Greg Kroah-Hartman
On Tue, Jun 23, 2020 at 02:33:48AM -0700, Rick Lindsley wrote: > On 6/22/20 11:02 PM, Greg Kroah-Hartman wrote: > > > First off, this is not my platform, and not my problem, so it's funny > > you ask me :) > > Wlll, not your platform perhaps but MAINTAINERS does list you > first and Tejun

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Rick Lindsley
On 6/22/20 11:02 PM, Greg Kroah-Hartman wrote: First off, this is not my platform, and not my problem, so it's funny you ask me :) Wlll, not your platform perhaps but MAINTAINERS does list you first and Tejun second as maintainers for kernfs. So in that sense, any patches would need to

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Ian Kent
On Tue, 2020-06-23 at 16:01 +0800, Ian Kent wrote: > On Tue, 2020-06-23 at 08:02 +0200, Greg Kroah-Hartman wrote: > > On Tue, Jun 23, 2020 at 01:09:08PM +0800, Ian Kent wrote: > > > On Mon, 2020-06-22 at 20:03 +0200, Greg Kroah-Hartman wrote: > > > > On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Ian Kent
On Tue, 2020-06-23 at 08:02 +0200, Greg Kroah-Hartman wrote: > On Tue, Jun 23, 2020 at 01:09:08PM +0800, Ian Kent wrote: > > On Mon, 2020-06-22 at 20:03 +0200, Greg Kroah-Hartman wrote: > > > On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun Heo wrote: > > > > Hello, Ian. > > > > > > > > On Sun,

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-23 Thread Greg Kroah-Hartman
On Tue, Jun 23, 2020 at 01:09:08PM +0800, Ian Kent wrote: > On Mon, 2020-06-22 at 20:03 +0200, Greg Kroah-Hartman wrote: > > On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun Heo wrote: > > > Hello, Ian. > > > > > > On Sun, Jun 21, 2020 at 12:55:33PM +0800, Ian Kent wrote: > > > > > > They are used

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Greg Kroah-Hartman
On Mon, Jun 22, 2020 at 02:27:38PM -0700, Rick Lindsley wrote: > > On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun Heo wrote: > > > It should be obvious that representing each consecutive memory range with a > > separate directory entry is far from an optimal way of representing > > something

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Ian Kent
On Mon, 2020-06-22 at 20:03 +0200, Greg Kroah-Hartman wrote: > On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun Heo wrote: > > Hello, Ian. > > > > On Sun, Jun 21, 2020 at 12:55:33PM +0800, Ian Kent wrote: > > > > > They are used for hotplugging and partitioning memory. The > > > > > size of > > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Rick Lindsley
On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun Heo wrote: It should be obvious that representing each consecutive memory range with a separate directory entry is far from an optimal way of representing something like this. It's outright silly. On 6/22/20 11:03 AM, Greg Kroah-Hartman wrote:

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Rick Lindsley
On 6/22/20 10:53 AM, Tejun Heo wrote: I don't know. The above highlights the absurdity of the approach itself to me. You seem to be aware of it too in writing: 250,000 "devices". Just because it is absurd doesn't mean it wasn't built that way :) I agree, and I'm trying to influence the next

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Greg Kroah-Hartman
On Mon, Jun 22, 2020 at 01:48:45PM -0400, Tejun Heo wrote: > Hello, Ian. > > On Sun, Jun 21, 2020 at 12:55:33PM +0800, Ian Kent wrote: > > > > They are used for hotplugging and partitioning memory. The size of > > > > the > > > > segments (and thus the number of them) is dictated by the > > > >

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Tejun Heo
On Fri, Jun 19, 2020 at 07:44:29PM -0700, Rick Lindsley wrote: > echo 0 > /sys/devices//system/memory/memory10374/online > > and boom - you've taken memory chunk 10374 offline. > > These changes are not just a whim. I used lockstat to measure contention > during boot. The addition of 250,000

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-22 Thread Tejun Heo
Hello, Ian. On Sun, Jun 21, 2020 at 12:55:33PM +0800, Ian Kent wrote: > > > They are used for hotplugging and partitioning memory. The size of > > > the > > > segments (and thus the number of them) is dictated by the > > > underlying > > > hardware. > > > > This sounds so bad. There gotta be a

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-20 Thread Ian Kent
On Fri, 2020-06-19 at 18:23 -0400, Tejun Heo wrote: > On Fri, Jun 19, 2020 at 01:41:39PM -0700, Rick Lindsley wrote: > > On 6/19/20 8:38 AM, Tejun Heo wrote: > > > > > I don't have strong objections to the series but the rationales > > > don't seem > > > particularly strong. It's solving a

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-20 Thread Ian Kent
On Fri, 2020-06-19 at 11:38 -0400, Tejun Heo wrote: > Hello, Ian. > > On Wed, Jun 17, 2020 at 03:37:43PM +0800, Ian Kent wrote: > > The series here tries to reduce the locking needed during path > > walks > > based on the assumption that there are many path walks with a > > fairly > > large

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-19 Thread Rick Lindsley
On 6/19/20 3:23 PM, Tejun Heo wrote: Spending 5 minutes during boot creating sysfs objects doesn't seem like a particularly good solution and I don't know whether anyone else would experience similar issues. Again, not necessarily against improving the scalability of kernfs code but the use

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-19 Thread Tejun Heo
On Fri, Jun 19, 2020 at 01:41:39PM -0700, Rick Lindsley wrote: > On 6/19/20 8:38 AM, Tejun Heo wrote: > > > I don't have strong objections to the series but the rationales don't seem > > particularly strong. It's solving a suspected problem but only half way. It > > isn't clear whether this can

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-19 Thread Rick Lindsley
On 6/19/20 8:38 AM, Tejun Heo wrote: I don't have strong objections to the series but the rationales don't seem particularly strong. It's solving a suspected problem but only half way. It isn't clear whether this can be the long term solution for the problem machine and whether it will benefit

Re: [PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-19 Thread Tejun Heo
Hello, Ian. On Wed, Jun 17, 2020 at 03:37:43PM +0800, Ian Kent wrote: > The series here tries to reduce the locking needed during path walks > based on the assumption that there are many path walks with a fairly > large portion of those for non-existent paths, as described above. > > That was

[PATCH v2 0/6] kernfs: proposed locking and concurrency improvement

2020-06-17 Thread Ian Kent
For very large IBM Power mainframe systems with hundreds of CPUs and TBs of RAM booting can take a very long time. Initial reports showed that booting a configuration of several hundred CPUs and 64TB of RAM would take more than 30 minutes and require kernel parameters of udev.children-max=1024