| Message ID | 1267172983-28721-4-git-send-email-Joakim.Tjernlund@transmode.se (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | d069cb4373fe0d451357c4d3769623a7564dfa9f |
| Headers | show |
On Fri, 2010-02-26 at 09:29 +0100, Joakim Tjernlund wrote: > Only the swap function cares about the ACCESSED bit in > the pte. Do not waste cycles updateting ACCESSED when swap > is not compiled into the kernel. > --- Your changeset comment is a bit misleading since the code isn't actually updating ACCESSED... it's testing if ACCESSED is set and goes to the higher level fault if not (which might then update ACCESSED). Cheers, Ben. > arch/powerpc/kernel/head_8xx.S | 6 ++++-- > 1 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S > index 84ca1d9..6478a96 100644 > --- a/arch/powerpc/kernel/head_8xx.S > +++ b/arch/powerpc/kernel/head_8xx.S > @@ -343,10 +343,11 @@ InstructionTLBMiss: > mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ > lwz r10, 0(r11) /* Get the pte */ > > +#ifdef CONFIG_SWAP > andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT > cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT > bne- cr0, 2f > - > +#endif > /* The Linux PTE won't go exactly into the MMU TLB. > * Software indicator bits 21 and 28 must be clear. > * Software indicator bits 24, 25, 26, and 27 must be > @@ -439,10 +440,11 @@ DataStoreTLBMiss: > * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5)); > * r10 = (r10 & ~PRESENT) | r11; > */ > +#ifdef CONFIG_SWAP > rlwinm r11, r10, 32-5, _PAGE_PRESENT > and r11, r11, r10 > rlwimi r10, r11, 0, _PAGE_PRESENT > - > +#endif > /* Honour kernel RO, User NA */ > /* 0x200 == Extended encoding, bit 22 */ > rlwimi r10, r10, 32-2, 0x200 /* Copy USER to bit 22, 0x200 */
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote on 2010/03/16 22:20:52: > > On Fri, 2010-02-26 at 09:29 +0100, Joakim Tjernlund wrote: > > Only the swap function cares about the ACCESSED bit in > > the pte. Do not waste cycles updateting ACCESSED when swap > > is not compiled into the kernel. > > --- > > Your changeset comment is a bit misleading since the code isn't actually > updating ACCESSED... it's testing if ACCESSED is set and goes to the > higher level fault if not (which might then update ACCESSED). Right, I did have one or two variants that did update ACCESSED that I experimented with, I guess that I got a bit confused by that. The jury is still out on whether this patch is an improvement or not. Jocke
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S index 84ca1d9..6478a96 100644 --- a/arch/powerpc/kernel/head_8xx.S +++ b/arch/powerpc/kernel/head_8xx.S @@ -343,10 +343,11 @@ InstructionTLBMiss: mfspr r11, SPRN_MD_TWC /* ....and get the pte address */ lwz r10, 0(r11) /* Get the pte */ +#ifdef CONFIG_SWAP andi. r11, r10, _PAGE_ACCESSED | _PAGE_PRESENT cmpwi cr0, r11, _PAGE_ACCESSED | _PAGE_PRESENT bne- cr0, 2f - +#endif /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 21 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be @@ -439,10 +440,11 @@ DataStoreTLBMiss: * r11 = ((r10 & PRESENT) & ((r10 & ACCESSED) >> 5)); * r10 = (r10 & ~PRESENT) | r11; */ +#ifdef CONFIG_SWAP rlwinm r11, r10, 32-5, _PAGE_PRESENT and r11, r11, r10 rlwimi r10, r11, 0, _PAGE_PRESENT - +#endif /* Honour kernel RO, User NA */ /* 0x200 == Extended encoding, bit 22 */ rlwimi r10, r10, 32-2, 0x200 /* Copy USER to bit 22, 0x200 */