smarter relatime updates

[Colin Watson]

I'm in the process of turning on relatime by default in the Ubuntu installer.

http://lwn.net/Articles/244829/ links to discussion of a patch by Ingo Molnar (http://people.redhat.com/mingo/relatime-patches/improve-relatime.patch) that makes atime updates a little bit smarter ("update atime if the previous atime value is older than a day"), which would avoid regressions in /tmp-reaping tools and popularity-contest. I thought this had been merged ages ago, but on looking at both our git and upstream I see that it hasn't. Could we merge this for 8.04, please?

Fedora includes this patch, and is probably a good source for an up-to-date copy:

  http://cvs.fedora.redhat.com/viewcvs/rpms/kernel/devel/linux-2.6-smarter-relatime.patch?rev=1.5&view=log

[Amit Kucheria (amitk)]

Patch is straighforward and disabled by default.

We can either enable CONFIG_DEFAULT_RELATIME to force all filesystems to use relatime or force it by writing to /proc/sys/kernel/default_relatime.

Else, only filesystems with the relatime option in /etc/fstab will use this.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 2.6.24-12.18

---------------
linux (2.6.24-12.18) hardy; urgency=low

  [Amit Kucheria]

  * Move Marvell 8686 and 8688 to LUM
  * Poulsbo: Sync patches with moblin/ume-hardy tree
  * Break if a patch fails to apply
  * SAUCE: implement smarter atime updates support
    - LP: #199427
  * Enable USB_PERSIST to allow devices with /root on usb to work with
    suspend
  * Enable USB_PERSIST across the board

  [Ben Collins]

  * build/config: Really fix ide on smp ppc configs
  * build/configs: Enable relatime config option for all flavors
  * build/abi: Ignore ide-core module for ppc, moved to built-in

  [Colin Ian King]

  * fix reversed logic for bbuild check leads to -j1 default
    - LP: #197040
  * Enable IDE_PMAC for powerpc-smp
    - LP: #196686
  * Disable CONFIG_USB_OHCI_HCD_SSB
    - LP: #182716
  * SAUCE: fix arcmsr + archttp64 calls dma_free_coherent() with irqs
    disabled - dmesg filled with warnings
    - LP: #194207

  [Jorge Boncompte [DTI2]]

  * Fix Messed multicast lists after dev_mc_sync/unsync
    - LP: #193468

  [Stefan Bader]

  * Add support for Apple Aluminium keyboards.
    - LP: #162083
  * SAUCE: Restore VT fonts on switch

  [Upstream Kernel Changes]

  * [NET]: Messed multicast lists after dev_mc_sync/unsync
  * KVM: x86 emulator: add support for group decoding
  * KVM: x86 emulator: group decoding for group 1A
  * KVM: x86 emulator: Group decoding for group 3
  * KVM: x86 emulator: Group decoding for groups 4 and 5
  * KVM: x86 emulator: add group 7 decoding
  * KVM: constify function pointer tables
  * KVM: Only x86 has pio
  * KVM: x86 emulator: group decoding for group 1 instructions
  * KVM: MMU: Decouple mmio from shadow page tables
  * KVM: Limit vcpu mmap size to one page on non-x86
  * KVM: VMX: Enable Virtual Processor Identification (VPID)
  * KVM: Use CONFIG_PREEMPT_NOTIFIERS around struct preempt_notifier
  * KVM: Disable pagefaults during copy_from_user_inatomic()
  * KVM: make EFER_RESERVED_BITS configurable for architecture code
  * KVM: align valid EFER bits with the features of the host system
  * KVM: allow access to EFER in 32bit KVM
  * kvm: i386 fix
  * KVM: export information about NPT to generic x86 code
  * KVM: MMU: make the __nonpaging_map function generic
  * KVM: export the load_pdptrs() function to modules
  * KVM: MMU: add TDP support to the KVM MMU
  * KVM: x86 emulator: Fix 'jmp abs'
  * KVM: x86 emulator: fix group 5 decoding
  * KVM: Fix kvm_arch_vcpu_ioctl_set_sregs so that set_cr0 works properly
  * KVM: Make the supported cpuid list a host property rather than a vm
    property
  * KVM: emulate access to MSR_IA32_MCG_CTL
  * KVM: remove the usage of the mmap_sem for the protection of the memory
    slots.
  * KVM: SVM: allocate the MSR permission map per VCPU
  * KVM: make MMU_DEBUG compile again
  * KVM: paravirtualized clocksource: host part
  * KVM: Add missing semicolon
  * KVM: x86 emulator: add ad_mask static inline
  * KVM: x86 emulator: make register_address, address_mask static inlines
  * KVM: x86 emulator: make register_address_increment and JMP_REL static
    inlines
  * KVM: Add API to retrieve the number of supported...