On Mon, Dec 01, 2008 at 05:48:05PM +0300, Alexey Starikovskiy wrote: > Christoph Lameter wrote: > >On Mon, 1 Dec 2008, Pekka Enberg wrote: > > > > > >>Why do you think Nick's patch is going to _increase_ memory consumption? > >>SLUB _already_ merges the ACPI caches with kmalloc caches so you won't > >>see any difference there. For SLAB, it's a gain because there's not > >>enough activity going on which results in lots of unused space in the > >>slabs (which is, btw, the reason SLUB does slab merging in the first > >>place). > >> > > > >The patch is going to increase memory consumption because the use of > >the kmalloc array means that the allocated object sizes are rounded up to > >the next power of two. > > > >I would recommend to keep the caches. Subsystem specific caches help to > >simplify debugging and track the memory allocated for various purposes in > >addition to saving the rounding up to power of two overhead. > >And with SLUB the creation of such caches usually does not require > >additional memory. > > > >Maybe it would be best to avoid kmalloc as much as possible. > > > > > Christoph, > Thanks for support, these were my thoughts, when I changed ACPICA to use > kmem_cache instead of > it's own on top of kmalloc 4 years ago... > Here are two acpi caches on my thinkpad z61m, IMHO any laptop will show > similar numbers: > > aystarik@thinkpad:~$ cat /proc/slabinfo | grep Acpi > Acpi-ParseExt 2856 2856 72 56 1 : tunables 0 0 > 0 : slabdata 51 51 0 > Acpi-Parse 170 170 48 85 1 : tunables 0 0 > 0 : slabdata 2 2 0 > > Size of first will become 96 and size of second will be 64 if kmalloc is > used, and we don't count ACPICA internal overhead. > Number of used blocks is not smallest in the list of slabs, actually it > is among the highest. Hmm. Acpi-Operand 2641 2773 64 59 1 : tunables 120 60 8 : slabdata 47 47 0 Acpi-ParseExt 0 0 64 59 1 : tunables 120 60 8 : slabdata 0 0 0 Acpi-Parse 0 0 40 92 1 : tunables 120 60 8 : slabdata 0 0 0 Acpi-State 0 0 80 48 1 : tunables 120 60 8 : slabdata 0 0 0 Acpi-Namespace 1711 1792 32 112 1 : tunables 120 60 8 : slabdata 16 16 0 Looks different for my thinkpad. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
