linux/drivers/base
Stephen Boyd a098ecd2fa firmware: support loading into a pre-allocated buffer
Some systems are memory constrained but they need to load very large
firmwares.  The firmware subsystem allows drivers to request this
firmware be loaded from the filesystem, but this requires that the
entire firmware be loaded into kernel memory first before it's provided
to the driver.  This can lead to a situation where we map the firmware
twice, once to load the firmware into kernel memory and once to copy the
firmware into the final resting place.

This creates needless memory pressure and delays loading because we have
to copy from kernel memory to somewhere else.  Let's add a
request_firmware_into_buf() API that allows drivers to request firmware
be loaded directly into a pre-allocated buffer.  This skips the
intermediate step of allocating a buffer in kernel memory to hold the
firmware image while it's read from the filesystem.  It also requires
that drivers know how much memory they'll require before requesting the
firmware and negates any benefits of firmware caching because the
firmware layer doesn't manage the buffer lifetime.

For a 16MB buffer, about half the time is spent performing a memcpy from
the buffer to the final resting place.  I see loading times go from
0.081171 seconds to 0.047696 seconds after applying this patch.  Plus
the vmalloc pressure is reduced.

This is based on a patch from Vikram Mulukutla on codeaurora.org:
  https://www.codeaurora.org/cgit/quic/la/kernel/msm-3.18/commit/drivers/base/firmware_class.c?h=rel/msm-3.18&id=0a328c5f6cd999f5c591f172216835636f39bcb5

Link: http://lkml.kernel.org/r/20160607164741.31849-4-stephen.boyd@linaro.org
Signed-off-by: Stephen Boyd <stephen.boyd@linaro.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Vikram Mulukutla <markivx@codeaurora.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-08-02 19:35:10 -04:00
..
power Merge branches 'pm-core', 'pm-clk', 'pm-domains' and 'pm-pci' 2016-07-25 13:45:27 +02:00
regmap Merge remote-tracking branches 'regmap/topic/bulk', 'regmap/topic/i2c', 'regmap/topic/iopoll', 'regmap/topic/irq' and 'regmap/topic/maintainers' into regmap-next 2016-07-15 13:44:47 +01:00
attribute_container.c attribute_container: fix missing blank lines after declarations 2015-03-25 14:35:09 +01:00
base.h PM / sleep: prohibit devices probing during suspend/hibernation 2015-11-30 14:47:22 +01:00
bus.c driver core: bus: use to_subsys_private and to_device_private_bus 2016-02-09 17:25:27 -08:00
cacheinfo.c cpu/cacheinfo: Fix teardown path 2015-09-17 06:06:54 -07:00
class.c class_find_device: fix reference to argument "match" 2015-09-29 15:23:14 +02:00
component.c Merge 4.5-rc4 into driver-core-next 2016-02-14 14:29:55 -08:00
container.c
core.c driver core: Do not overwrite secondary fwnode with NULL if it is set 2015-12-07 02:29:23 +01:00
cpu.c drivers/base/cpu.c: use __cpu_*_mask directly 2016-01-20 17:09:18 -08:00
dd.c Revert "base: dd: don't remove driver_data in -EPROBE_DEFER case" 2016-05-03 08:06:06 -07:00
devcoredump.c devcoredump: add scatterlist support 2016-04-15 11:20:32 -07:00
devres.c devm: make allocations numa aware by default 2015-10-09 17:00:33 -04:00
devtmpfs.c wrappers for ->i_mutex access 2016-01-22 18:04:28 -05:00
dma-coherent.c drivers: dma-coherent: use memset_io for DMA_MEMORY_IO mappings 2016-03-22 15:36:02 -07:00
dma-contiguous.c driver core update for 4.4-rc1 2015-11-04 21:50:37 -08:00
dma-mapping.c dma-mapping: remove <asm-generic/dma-coherent.h> 2016-01-20 17:09:18 -08:00
driver.c driver core: add missing blank line after declaration 2015-03-25 14:36:30 +01:00
firmware_class.c firmware: support loading into a pre-allocated buffer 2016-08-02 19:35:10 -04:00
firmware.c
hypervisor.c
init.c drivers: of/base: move of_init to driver_init 2015-05-26 19:55:56 -07:00
isa.c isa: Call isa_bus_init before dependent ISA bus drivers register 2016-06-17 20:47:11 -07:00
Kconfig
Makefile isa: Allow ISA-style drivers on modern systems 2016-06-17 20:21:12 -07:00
map.c drivers: base: map: Use kmalloc_array instead of kmalloc 2015-03-25 14:35:08 +01:00
memory.c memory-hotplug: use zone_can_shift() for sysfs valid_zones attribute 2016-07-26 16:19:19 -07:00
module.c base: make module_create_drivers_dir race-free 2016-06-15 19:21:31 -07:00
node.c treewide: replace obsolete _refok by __ref 2016-08-02 17:31:41 -04:00
pinctrl.c drivers/pinctrl: Add the concept of an "init" state 2015-10-27 11:24:23 +01:00
platform-msi.c base: Export platform_msi_domain_[alloc,free]_irqs 2016-01-26 16:33:25 +01:00
platform.c device property: don't bother the drivers with struct property_set 2016-04-09 03:10:50 +02:00
property.c device property: Add function to search for named child of device 2016-06-26 12:39:03 +01:00
soc.c base: soc: siplify ida usage 2015-10-04 19:42:22 +01:00
syscore.c
topology.c topology/sysfs: provide drawer id and siblings attributes 2016-06-13 15:58:27 +02:00
transport_class.c