mainlining shenanigans
9300d9c4ad
Pavel Tatashin says: ==================== sparc64: Early boot timestamp Changelog: v2 - v3: - __aligned(64) -> __cacheline_aligned - Replaced in sched_clock() wmb() with barrier() v1 - v2: - Early boot timestamps are now available on all 64-bit sparc processors - New hot-patched get_tick() function. This patch set: - enables early boot timestamps on SPARC, - adds offset so we count time from zero, the same as it is done on other platforms - improves the performance by inling, hot patching, and combining loads into the same cacheline. (and few other optimizations). So, the final performance of sched_clock() is faster than now: the fewer number of loads, and all of them are coming from the same cacheline. Loads can run while we are reading tick value, and we do not do function call. Current sched_clock(): sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x250 ], %g1 ldx [ %g1 ], %g1 call %g1 nop sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x300 ], %g1 mulx %o0, %g1, %g1 rett %i7 + 8 srlx %g1, 0xa, %o0 Final sched_clock(): sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x2c8 ], %g2 ldx [ %g1 + 0x2c0 ], %g1 b 42f638 <sched_clock+0x44> rd %asr24, %i0 ... sllx %i0, 1, %i0 srlx %i0, 1, %i0 mulx %i0, %g1, %i0 srlx %i0, 0xa, %i0 rett %i7 + 8 sub %o0, %g2, %o0 ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.