Re: [PATCH] mm: PageLRU can be non-atomic bit operation

On Mon, 23 Apr 2007, Hisashi Hifumi wrote:
> 
> PageLRU flag operation is protected by zone->lru_lock, so
> SetPageLRU/ClearPageLRU
> can be replaced to __SetPageLRU/__ClearPageLRU non-atomic bit operation.

No.  The PG_lru flag bit is just one bit amongst many others:
what of concurrent operations changing other bits in that same
unsigned long e.g. trying to lock the page by setting PG_locked?
There are some places where such micro-optimizations can be made
(typically while first allocating the page); but in general, no.

Hugh
-
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: [PATCH] mm: PageLRU can be non-atomic bit operation
    • From: Hisashi Hifumi <[email protected]>

• References:
  • [PATCH] mm: PageLRU can be non-atomic bit operation
    • From: Hisashi Hifumi <[email protected]>

• Prev by Date: Re: [PATCH 7/8] Kconfig: silicon backplane dependency.
• Next by Date: Re: [PATCH 7/8] Kconfig: silicon backplane dependency.
• Previous by thread: [PATCH] mm: PageLRU can be non-atomic bit operation
• Next by thread: Re: [PATCH] mm: PageLRU can be non-atomic bit operation
• 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]