Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices:
OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
bdacfaf26d
The kernel can allocate a lot of struct perf_event when profiling. For example, 256 cpu x 8 events x 20 cgroups = 40K instances of the struct would be allocated on a large system. The size of struct perf_event in my setup is 1152 byte. As it's allocated by kmalloc, the actual allocation size would be rounded up to 2K. Then there's 896 byte (~43%) of waste per instance resulting in total ~35MB with 40K instances. We can create a dedicated kmem_cache to avoid such a big unnecessary memory consumption. With this change, I can see below (note this machine has 112 cpus). # grep perf_event /proc/slabinfo perf_event 224 784 1152 7 2 : tunables 24 12 8 : slabdata 112 112 0 The sixth column is pages-per-slab which is 2, and the fifth column is obj-per-slab which is 7. Thus actually it can use 1152 x 7 = 8064 byte in the 8K, and wasted memory is (8192 - 8064) / 7 = ~18 byte per instance. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210311115413.444407-1-namhyung@kernel.org |
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| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.