Re: [RESEND] shm: shm exit scalability fixes

2014-06-18 Thread Andrew Morton
On Tue, 17 Jun 2014 12:27:44 -0500 Jack Miller wrote: > [ RESEND note: Adding relevant CCs, fixed a couple of typos in commit message, > patches unchanged. Original intro follows. ] > > All - > > This is small set of patches our team has had kicking around for a few > versions > internally tha

Re: [RESEND] shm: shm exit scalability fixes

2014-06-17 Thread Michael Ellerman
On Wed, 2014-06-18 at 12:53 +1000, Anton Blanchard wrote: > > I normally wouldn't mind optimizing synthetic cases like this, but a > > quick look at patch 1/3 shows that we're adding an extra overhead (16 > > bytes) in the task_struct. > > > We have the shmmni limit (and friends) for that. > > If

Re: [RESEND] shm: shm exit scalability fixes

2014-06-17 Thread Anton Blanchard
Hi David, > > Anton wrote a simple test to cause the issue: > > > > http://ozlabs.org/~anton/junkcode/bust_shm_exit.c > > I'm actually in the process of adding shm microbenchmarks to > perf-bench so I might steal this :-) Sounds good! > Are you seeing this issue in any real world setups? While

Re: [RESEND] shm: shm exit scalability fixes

2014-06-17 Thread Davidlohr Bueso
On Tue, 2014-06-17 at 14:55 -0500, Jack Miller wrote: > Even if this is synthetic, the testcase could also be seen as proof of an > unprivileged denial of service as an arbitrary user could run bust_shm_exit > and subsequently start overloading the system. We have the shmmni limit (and friends) fo

Re: [RESEND] shm: shm exit scalability fixes

2014-06-17 Thread Jack Miller
On Tue, Jun 17, 2014 at 10:48:32AM -0700, Davidlohr Bueso wrote: > On Tue, 2014-06-17 at 12:27 -0500, Jack Miller wrote: > > [ RESEND note: Adding relevant CCs, fixed a couple of typos in commit > > message, > > patches unchanged. Original intro follows. ] > > > > All - > > > > This is small set

Re: [RESEND] shm: shm exit scalability fixes

2014-06-17 Thread Davidlohr Bueso
On Tue, 2014-06-17 at 12:27 -0500, Jack Miller wrote: > [ RESEND note: Adding relevant CCs, fixed a couple of typos in commit message, > patches unchanged. Original intro follows. ] > > All - > > This is small set of patches our team has had kicking around for a few > versions > internally that

[RESEND] shm: shm exit scalability fixes

2014-06-17 Thread Jack Miller
[ RESEND note: Adding relevant CCs, fixed a couple of typos in commit message, patches unchanged. Original intro follows. ] All - This is small set of patches our team has had kicking around for a few versions internally that fixes tasks getting hung on shm_exit when there are many threads hammer