Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c

On Tue, 14 Aug 2007, Andi Kleen wrote:

> > But that still creates lots of overhead each time we take the lru lock!
> 
> A lot of overhead in what way? Setting a flag in a cache hot
> per CPU data variable shouldn't be more than a few cycles.

Could you be a bit more specific? Where do you want to place the data?

What we are talking about is

atomic_inc(&zone->reclaim_cpu[smp_processor_id()]);
smp_wmb();
spin_lock(&zone->lru_lock);

....

spin_unlock(&zone_lru_lock);
smp_wmb();
atomic_dec(&zone->reclaim_cpu[smp_processor_id()]);

That is not light weight.

-
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/

---

• Follow-Ups:
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>

• References:
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Christoph Lameter <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Christoph Lameter <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Christoph Lameter <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Christoph Lameter <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Christoph Lameter <[email protected]>
  • Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
    • From: Andi Kleen <[email protected]>

• Prev by Date: Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
• Next by Date: Re: 2.6.23-rc3 - CONFIG_VMI broken
• Previous by thread: Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
• Next by thread: Re: [RFC 4/9] Atomic reclaim: Save irq flags in vmscan.c
• 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]