From 6e74d2bf5a265113ca54a8323783d2f3fdde96b7 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Mon, 9 May 2022 18:20:54 -0700 Subject: mm/damon/core: add a new callback for watermarks checks Patch series "mm/damon: Support online tuning". Effects of DAMON and DAMON-based Operation Schemes highly depends on the configurations. Wrong configurations could even result in unexpected efficiency degradations. For finding a best configuration, repeating incremental configuration changes and results measurements, in other words, online tuning, could be helpful. Nevertheless, DAMON kernel API supports only restrictive online tuning. Worse yet, the sysfs-based DAMON user interface doesn't support online tuning at all. DAMON_RECLAIM also doesn't support online tuning. This patchset makes the DAMON kernel API, DAMON sysfs interface, and DAMON_RECLAIM supports online tuning. Sequence of patches ------------------- First two patches enhance DAMON online tuning for kernel API users. Specifically, patch 1 let kernel API users to be able to do DAMON online tuning without a restriction, and patch 2 makes error handling easier. Following seven patches (patches 3-9) refactor code for better readability and easier reuse of code fragments that will be useful for online tuning support. Patch 10 introduces DAMON callback based user request handling structure for DAMON sysfs interface, and patch 11 enables DAMON online tuning via DAMON sysfs interface. Documentation patch (patch 12) for usage of it follows. Patch 13 enables online tuning of DAMON_RECLAIM and finally patch 14 documents the DAMON_RECLAIM online tuning usage. This patch (of 14): For updating input parameters for running DAMON contexts, DAMON kernel API users can use the contexts' callbacks, as it is the safe place for context internal data accesses. When the context has DAMON-based operation schemes and all schemes are deactivated due to their watermarks, however, DAMON does nothing but only watermarks checks. As a result, no callbacks will be called back, and therefore the kernel API users cannot update the input parameters including monitoring attributes, DAMON-based operation schemes, and watermarks. To let users easily update such DAMON input parameters in such a case, this commit adds a new callback, 'after_wmarks_check()'. It will be called after each watermarks check. Users can do the online input parameters update in the callback even under the schemes deactivated case. Link: https://lkml.kernel.org/r/20220429160606.127307-2-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- mm/damon/core.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'mm/damon/core.c') diff --git a/mm/damon/core.c b/mm/damon/core.c index 997cf7b17779..44fe7e452a1e 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1051,6 +1051,10 @@ static int kdamond_wait_activation(struct damon_ctx *ctx) return 0; kdamond_usleep(min_wait_time); + + if (ctx->callback.after_wmarks_check && + ctx->callback.after_wmarks_check(ctx)) + break; } return -EBUSY; } @@ -1077,8 +1081,10 @@ static int kdamond_fn(void *data) sz_limit = damon_region_sz_limit(ctx); while (!kdamond_need_stop(ctx) && !done) { - if (kdamond_wait_activation(ctx)) + if (kdamond_wait_activation(ctx)) { + done = true; continue; + } if (ctx->ops.prepare_access_checks) ctx->ops.prepare_access_checks(ctx); -- cgit v1.2.3