Dear SeongJae Park, SeongJae Park <sj@xxxxxxxxxx> writes: > Hi Piyush, > > On Tue, 13 Jun 2023 12:18:48 +0530 Piyush Sachdeva <piyushs@xxxxxxxxxxxxx> wrote: > >> Dear Mr. SeongJae Park, >> I hope this email finds you well. > > It did, thank you for this email :) > >> >> For the last few months, I have been looking at DAMON from an end-users >> perspective and a developer's PoV. Most recently, I was focusing on >> `lru_sort.c` module that uses the `lru_prio` and `lru_deprio` operations >> which result in a more precise reclaim. In my understanding, enabling >> the "lru_sort.c" module would make intelligent decisions based on the >> access frequency of the pages and end up preventing hot page >> swaps. Hence, when integrated with an LRU algorithm, it should improve >> it. >> >> If you could share any test/benchmark that you might have run to verify >> the above assumption? > > Yes, of course. I will share those soon. > >> I did find the result numbers you posted (link below), but that doesn't >> mention the "plrus-*" scheme numbers. It also doesn't have numbers for >> running the `pageout` operation on the entire physical address space (paddr) >> i.e. the `pprcl` scheme. So, if you can link those too, it would be amazing. > > We run an automated test[1] every day, against the latest damon/next tree. And > the page you linked is the output of the test. The latet version contains the > results from `pprcl`[2] and `plrus`[3], but I was too lazy at updating the > document, sorry. I will try to clean up the mess as soon as possible. > >> >> Can you also share any real-world (memory-management specific) workload >> results that you would have used with DAMON in your experiments? Like >> either MongoDB or memcached over Parsec3.0 (including splash2x) - which, >> in my understanding, is less memory intensive and more architecture >> inclined. > > On my personal testing setup, I'm using only parsec3 and splash2x at the > moment. We heard some production DB system is using DAMON_RECLAIM and achieved > about 20% memory footprint reduction, though. > Are you aware of the specifications of the DB system that you are mentioning? 20% is an amazing number and if possible I would like to know more about the details of the workload. >> >> I also had a question regarding schemes - A scheme is highly tweakable, >> and it's what the efficiency of DAMON rests upon. The more precise the >> scheme, the more efficient DAMON will be. Hence, I'd be thankful if you >> can help me derive a config that would provide the best results. > > Very good point. Unfortunately, repeats of experience and adjustment is the > only way as of now, like other tuning practices. Nevertheless, DAMOS supports > some safeguards such as quotas[4], watermarks[5], and filters[6]. Because > quotas feature provides prioritization, setting the access pattern a little > wide, and more focusing on tuning of the quotas might be a good practice. > > I'm trying to add some more easy-to-use intuitive tuning knobs, including > feedback-based quota auto-tuning, which I shared the rough idea at LSFMM[7]. > I did go through your presentation and the summary article on lwn.net . The feedback-mechanism based self-tuning does sound ingriguing and promising to me. >> Hope to hear from you soon. > > Thank you again for this great questions. Please feel free to ask any question > or helps :) > > [1] https://github.com/awslabs/damon-tests/blob/next/perf/full_run.sh > [2] https://github.com/awslabs/damon-tests/blob/next/perf/schemes/pdarc_v4_2_2.json > [3] https://github.com/awslabs/damon-tests/blob/next/perf/schemes/plrus-2.json > [4] https://www.kernel.org/doc/html/next/mm/damon/design.html#quotas > [5] https://www.kernel.org/doc/html/next/mm/damon/design.html#watermarks > [6] https://www.kernel.org/doc/html/next/mm/damon/design.html#filters > [7] https://lwn.net/Articles/931769/ > > > Thanks, > SJ > >> >> Test results: https://damonitor.github.io/test/result/perf/latest/html/ >> >> -- >> Regards, >> Piyush Sachdeva >> Thank you for the information and all the links. -- Regards, Piyush Sachdeva
