Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats

On Fri, 30 Jun 2006 23:37:10 -0400
Shailabh Nagar <[email protected]> wrote:

> >Set aside the implementation details and ask "what is a good design"?
> >
> >A kernel-wide constant, whether determined at build-time or by a /proc poke
> >isn't a nice design.
> >
> >Can we permit userspace to send in a netlink message describing a cpumask? 
> >That's back-compatible.
> >  
> >
> Yes, that should be doable. And passing in a cpumask is much better 
> since we no longer
> have to maintain mappings.
> 
> So the strawman is:
> Listener bind()s to genetlink using its real pid.
> Sends a separate "registration" message with cpumask to listen to. 
> Kernel stores (real) pid and cpumask.
> During task exit, kernel goes through each registered listener (small 
> list) and decides which
> one needs to get this exit data and calls a genetlink_unicast to each 
> one that does need it.
> 
> If number of listeners is small, the lookups should be swift enough. If 
> it grows large, we
> can consider a fancier lookup (but there I go again, delving into 
> implementation too early :-)

We'll need a map.

1024 CPUs, 1024 listeners, 1000 exits/sec/CPU and we're up to a million
operations per second per CPU.  Meltdown.

But it's a pretty simple map.  A per-cpu array of pointers to the head of a
linked list.  One lock for each CPU's list.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

---

• References:
  • [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Jay Lan <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Jay Lan <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Jay Lan <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Jay Lan <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Jay Lan <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Paul Jackson <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: [email protected]
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Paul Jackson <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Andrew Morton <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>
  • Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
    • From: Shailabh Nagar <[email protected]>

• Prev by Date: Re: [2.6 patch] mm/mmzone.c: EXPORT_UNUSED_SYMBOL
• Next by Date: Re: [PATCH] sched.h: increment TASK_COMM_LEN to 20 bytes
• Previous by thread: Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
• Next by thread: Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats
• Index(es):
  • Date
  • Thread

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]