Calling alloc_bootmem() for tiny chunks of memory over and over is really
slow; on an XO-1, it caused the time between when the kernel started
booting and when the display came alive (post-lxfb probe) to increase
to 44s. This patch optimizes the prom_early_alloc function by
calling alloc_bootmem for 4k-sized blocks of memory, and handing out
chunks of that to callers. With this patch, the time between kernel load
and display initialization decreased to 23s. If there's a better way to
do this early in the boot process, please let me know.
(Note: increasing the chunk size to 16k didn't noticably affect boot time,
and wasted 9k.)
v4: clarify comment, requested by hpa
v3: fix wasted memory buglet found by Milton Miller, and style fix.
v2: reorder prom_early_alloc as suggested by Grant.
Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <20101129153951.74202a84@queued.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Make use of PROC_DEVICETREE to export the tree, and sparc's PROMTREE code to
call into OLPC's Open Firmware to build the tree.
v5: fix buglet with root node check (introduced in v4)
v4: address some minor style issues pointed out by Grant, and explicitly cast
negative phandle checks to s32.
v3: rename olpc_prom to olpc_dt
- rework Kconfig entries
- drop devtree build hook from proc, instead adding a call to x86's
paging_init (similarly to how sparc64 does it)
- switch allocation from using slab to alloc_bootmem. this allows
the DT to be built earlier during boot (during setup_arch); the
downside is that there are some 1200 bootmem reservations that are
done during boot. Not ideal..
- add a helper olpc_ofw_is_installed function to test for the
existence and successful detection of OLPC's OFW.
Signed-off-by: Andres Salomon <dilinger@queued.net>
LKML-Reference: <20101116220952.26526a80@queued.net>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
