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Shutemov" , Thomas Gleixner Cc: ardb@kernel.org, bp@alien8.de, brijesh.singh@amd.com, corbet@lwn.net, dave.hansen@linux.intel.com, hpa@zytor.com, jan.kiszka@siemens.com, jgross@suse.com, kbingham@kernel.org, linux-doc@vger.kernel.org, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, luto@kernel.org, michael.roth@amd.com, mingo@redhat.com, peterz@infradead.org, rick.p.edgecombe@intel.com, sandipan.das@amd.com, thomas.lendacky@amd.com, x86@kernel.org References: <80734605-1926-4ac7-9c63-006fe3ea6b6a@amd.com> <87wml16hye.ffs@tglx> <5b031938-9c82-4f09-b5dc-c45bc7fe6e07@amd.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <5b031938-9c82-4f09-b5dc-c45bc7fe6e07@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: mh8ry65as9ydj5t913juzaq44hsxny1m X-Rspam-User: X-Rspamd-Queue-Id: E964A4001E X-Rspamd-Server: rspam02 X-HE-Tag: 1730388954-92784 X-HE-Meta: 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 AL1DFNHy sZJ7Wyi0NgcQZ55AtaSBGXxl2H7miSDraeBemEtPs+QD9O33qGXs3eXVhIvxarfnbM6/78AjEAZWK53RjJk8qWhe+CebSHSyPR2GzUZQ7/oIhTHFxyCsGchkcn8nyopKbZAhXHHuZ/ymQIo9XfnB/aypGeIriCjt+WNM33XB0kTVpfzZn9W2n9tuha8qQi5DFVeSPMgMwo7ByJ5E= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/31/24 10:45, Shivank Garg wrote: > It would also be nice to get perf traces. Maybe it is purely SW issue. Cycle counts aren't going to help much here. For instance, if 5-level paging makes *ALL* TLB misses slower, you would just see a regression in any code that misses the TLB, which could show up all over. On Intel we have some PMU events like this: dtlb_store_misses.walk_active [Cycles when at least one PMH is busy with a page walk for a store] (there's a load side one as well). If a page walk gets more expensive, you can see it there. Note that this doesn't actually tell you how much time the core spent _waiting_ for a page walk to complete. If all the speculation magic works perfectly in your favor, you could have the PMH busy 100% of cycles but never had the core waiting on it. So could we drill down a level in the "perf traces" please, and gather some of the relevant performance counters and not just cycles?