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Zhen Lei 28fdfda791 kallsyms: Improve the performance of kallsyms_lookup_name()
[ Upstream commit 60443c88f3a89fd303a9e8c0e84895910675c316 ]

Currently, to search for a symbol, we need to expand the symbols in
'kallsyms_names' one by one, and then use the expanded string for
comparison. It's O(n).

If we sort names in ascending order like addresses, we can also use
binary search. It's O(log(n)).

In order not to change the implementation of "/proc/kallsyms", the table
kallsyms_names[] is still stored in a one-to-one correspondence with the
address in ascending order.

Add array kallsyms_seqs_of_names[], it's indexed by the sequence number
of the sorted names, and the corresponding content is the sequence number
of the sorted addresses. For example:
Assume that the index of NameX in array kallsyms_seqs_of_names[] is 'i',
the content of kallsyms_seqs_of_names[i] is 'k', then the corresponding
address of NameX is kallsyms_addresses[k]. The offset in kallsyms_names[]
is get_symbol_offset(k).

Note that the memory usage will increase by (4 * kallsyms_num_syms)
bytes, the next two patches will reduce (1 * kallsyms_num_syms) bytes
and properly handle the case CONFIG_LTO_CLANG=y.

Performance test results: (x86)
Before:
min=234, max=10364402, avg=5206926
min=267, max=11168517, avg=5207587
After:
min=1016, max=90894, avg=7272
min=1014, max=93470, avg=7293

The average lookup performance of kallsyms_lookup_name() improved 715x.

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Stable-dep-of: 8cc32a9bbf29 ("kallsyms: strip LTO-only suffixes from promoted global functions")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-07-27 08:50:39 +02:00
arch MIPS: dec: prom: Address -Warray-bounds warning 2023-07-27 08:50:33 +02:00
block blk-crypto: use dynamic lock class for blk_crypto_profile::lock 2023-07-23 13:49:21 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:21:42 +02:00
Documentation sched/psi: Allow unprivileged polling of N*2s period 2023-07-27 08:50:38 +02:00
drivers spi: s3c64xx: clear loopback bit after loopback test 2023-07-27 08:50:39 +02:00
fs btrfs: be a bit more careful when setting mirror_num_ret in btrfs_map_block 2023-07-27 08:50:39 +02:00
include sched/psi: use kernfs polling functions for PSI trigger polling 2023-07-27 08:50:38 +02:00
init gcc: disable '-Warray-bounds' for gcc-13 too 2023-04-26 14:28:43 +02:00
io_uring io_uring: treat -EAGAIN for REQ_F_NOWAIT as final for io-wq 2023-07-27 08:50:23 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel kallsyms: Improve the performance of kallsyms_lookup_name() 2023-07-27 08:50:39 +02:00
lib maple_tree: set the node limit when creating a new root node 2023-07-27 08:50:24 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm kasan: add kasan_tag_mismatch prototype 2023-07-23 13:49:32 +02:00
net wifi: wext-core: Fix -Wstringop-overflow warning in ioctl_standard_iw_point() 2023-07-27 08:50:35 +02:00
rust rust: kernel: Mark rust_fmt_argument as extern "C" 2023-04-26 14:28:38 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:49:44 +02:00
scripts kallsyms: Improve the performance of kallsyms_lookup_name() 2023-07-27 08:50:39 +02:00
security keys: Fix linking a duplicate key to a keyring's assoc_array 2023-07-27 08:50:24 +02:00
sound ASoC: qcom: q6apm: do not close GPR port before closing graph 2023-07-27 08:50:37 +02:00
tools perf build: Fix library not found error when using CSLIBS 2023-07-27 08:50:39 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Avoid illegal stage2 mapping on invalid memory slot 2023-06-28 11:12:23 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS smb: move client and server files to common directory fs/smb 2023-06-28 11:12:40 +02:00
Makefile Linux 6.1.41 2023-07-24 18:55:35 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.