forked from Minki/linux
57208e5e25
The entire logic that represent graph links were developed on a time where there were no needs to dynamic remove links. So, although links are created/removed one by one via some functions, they're stored as an array inside the entity struct. As the array may grow, there's a logic inside the code that checks if the amount of space is not enough to store the needed links. If it isn't the core uses krealloc() to change the size of the link, with is bad, as it leaves the memory fragmented. So, convert links into a list. Also, currently, both source and sink entities need the link at the graph traversal logic inside media_entity. So there's a logic duplicating all links. That makes it to spend twice the memory needed. This is not a big deal for today's usage, where the number of links are not big. Yet, if during the MC workshop discussions, it was said that IIO graphs could have up to 4,000 entities. So, we may want to remove the duplication on some future. The problem is that it would require a separate linked list to store the backlinks inside the entity, or to use a more complex algorithm to do graph backlink traversal, with is something that the current graph traversal inside the core can't cope with. So, let's postpone a such change if/when it is actually needed. It should also be noticed that the media_link structure uses 44 bytes on 32-bit architectures and 84 bytes on 64-bit architecture. It will thus be allocated out of the 64-bytes and 96-bytes pools respectively. That's a 12.5% memory waste on 64-bit architectures and 31.25% on 32-bit architecture. A linked list is less efficient than an array in this case, but this could later be optimized if we can get rid of the reverse links (with would reduce memory allocation by 50%). Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> |
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| .. | ||
| blackfin | ||
| davinci | ||
| drv-intf | ||
| i2c | ||
| i2c-addr.h | ||
| lirc_dev.h | ||
| lirc.h | ||
| media-device.h | ||
| media-devnode.h | ||
| media-entity.h | ||
| rc-core.h | ||
| rc-map.h | ||
| soc_camera.h | ||
| tuner-types.h | ||
| tuner.h | ||
| tveeprom.h | ||
| v4l2-async.h | ||
| v4l2-clk.h | ||
| v4l2-common.h | ||
| v4l2-ctrls.h | ||
| v4l2-dev.h | ||
| v4l2-device.h | ||
| v4l2-dv-timings.h | ||
| v4l2-event.h | ||
| v4l2-fh.h | ||
| v4l2-flash-led-class.h | ||
| v4l2-image-sizes.h | ||
| v4l2-ioctl.h | ||
| v4l2-mediabus.h | ||
| v4l2-mem2mem.h | ||
| v4l2-of.h | ||
| v4l2-subdev.h | ||
| videobuf2-core.h | ||
| videobuf2-dma-contig.h | ||
| videobuf2-dma-sg.h | ||
| videobuf2-dvb.h | ||
| videobuf2-memops.h | ||
| videobuf2-v4l2.h | ||
| videobuf2-vmalloc.h | ||
| videobuf-core.h | ||
| videobuf-dma-contig.h | ||
| videobuf-dma-sg.h | ||
| videobuf-dvb.h | ||
| videobuf-vmalloc.h | ||