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In timer_64.c tick functions are access via pointer (tick_ops), every time clock is read, there is one extra load to get to the function. This patch optimizes it, by accessing functions pointer from value. Current ched_clock(): sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x250 ], %g1 ! <tick_ops> ldx [ %g1 ], %g1 call %g1 nop sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x300 ], %g1 ! <timer_ticks_per_nsec_quotient> mulx %o0, %g1, %g1 rett %i7 + 8 srlx %g1, 0xa, %o0 New sched_clock(): sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x340 ], %g1 call %g1 nop sethi %hi(0xb9b400), %g1 ldx [ %g1 + 0x378 ], %g1 mulx %o0, %g1, %g1 rett %i7 + 8 srlx %g1, 0xa, %o0 Before three loads, now two loads. Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com> Reviewed-by: Steven Sistare <steven.sistare@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.