e2a366a4b0
Update CQ head with pre-increment operator. This saves subtraction of 1 and a few registers. Also update phase with "^= 1". This generates only one RMW instruction. ffffffff815ba150 <nvme_update_cq_head>: ffffffff815ba150: 0f b7 47 70 movzx eax,WORD PTR [rdi+0x70] ffffffff815ba154: 83 c0 01 add eax,0x1 ffffffff815ba157: 66 89 47 70 mov WORD PTR [rdi+0x70],ax ffffffff815ba15b: 66 3b 47 68 cmp ax,WORD PTR [rdi+0x68] ffffffff815ba15f: 74 01 je ffffffff815ba162 <nvme_update_cq_head+0x12> ffffffff815ba161: c3 ret ffffffff815ba162: 31 c0 xor eax,eax ffffffff815ba164: 80 77 74 01 ===> xor BYTE PTR [rdi+0x74],0x1 ffffffff815ba168: 66 89 47 70 mov WORD PTR [rdi+0x70],ax ffffffff815ba16c: c3 ret add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-119 (-119) Function old new delta nvme_poll 690 678 -12 nvme_dev_disable 1230 1177 -53 nvme_irq 613 559 -54 Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
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.