| Message ID | 20220513171811.730-4-mkoutny@suse.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | memcontrol selftests fixups | expand |
On Fri, May 13, 2022 at 07:18:10PM +0200, Michal Koutny wrote: > The numbers are not easy to derive in a closed form (certainly mere > protections ratios do not apply), therefore use a simulation to obtain > expected numbers. > > The new values make the protection tests succeed more precisely. > > % run as: octave-cli script > % > % Input configurations > % ------------------- > % E parent effective protection > % n nominal protection of siblings set at the givel level > % c current consumption -,,- > > % example from testcase (values in GB) > E = 50 / 1024; > n = [75 25 0 500 ] / 1024; > c = [50 50 50 0] / 1024; > > % Reclaim parameters > % ------------------ > > % Minimal reclaim amount (GB) > cluster = 32*4 / 2**20; > > % Reclaim coefficient (think as 0.5^sc->priority) > alpha = .1 > > % Simulation parameters > % --------------------- > epsilon = 1e-7; > timeout = 1000; > > % Simulation loop > % --------------------- > % Simulation assumes siblings consumed the initial amount of memory (w/out > % reclaim) and then the reclaim starts, all memory is reclaimable, i.e. treated > % same. It simulates only non-low reclaim and assumes all memory.min = 0. > > ch = []; > eh = []; > rh = []; > > for t = 1:timeout > % low_usage > u = min(c, n); > siblings = sum(u); > > % effective_protection() > protected = min(n, c); % start with nominal > e = protected * min(1, E / siblings); % normalize overcommit > > % recursive protection > unclaimed = max(0, E - siblings); > parent_overuse = sum(c) - siblings; > if (unclaimed > 0 && parent_overuse > 0) > overuse = max(0, c - protected); > e += unclaimed * (overuse / parent_overuse); > endif > > % get_scan_count() > r = alpha * c; % assume all memory is in a single LRU list > > % commit 1bc63fb1272b ("mm, memcg: make scan aggression always exclude protection") > sz = max(e, c); > r .*= (1 - (e+epsilon) ./ (sz+epsilon)); > > % uncomment to debug prints > % e, c, r > > % nothing to reclaim, reached equilibrium > if max(r) < epsilon > break; > endif > > % SWAP_CLUSTER_MAX > r = max(r, (r > epsilon) .* cluster); > % XXX here I do parallel reclaim of all siblings > % in reality reclaim is serialized and each sibling recalculates own residual > c = max(c - r, 0); > > ch = [ch ; c]; > eh = [eh ; e]; > rh = [rh ; r]; > endfor > > t > c, e This is a cool stuff! How about to place it into a separate file and add a comment into the code with a reference? Thanks!
diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c index eba252fa64ac..9ffacf024bbd 100644 --- a/tools/testing/selftests/cgroup/test_memcontrol.c +++ b/tools/testing/selftests/cgroup/test_memcontrol.c @@ -260,9 +260,9 @@ static int cg_test_proc_killed(const char *cgroup) * memory pressure in it. * * A/B memory.current ~= 50M - * A/B/C memory.current ~= 33M - * A/B/D memory.current ~= 17M - * A/B/F memory.current ~= 0 + * A/B/C memory.current ~= 29M + * A/B/D memory.current ~= 21M + * A/B/E memory.current ~= 0 * * After that it tries to allocate more than there is * unprotected memory in A available, and checks @@ -365,10 +365,10 @@ static int test_memcg_min(const char *root) for (i = 0; i < ARRAY_SIZE(children); i++) c[i] = cg_read_long(children[i], "memory.current"); - if (!values_close(c[0], MB(33), 10)) + if (!values_close(c[0], MB(29), 10)) goto cleanup; - if (!values_close(c[1], MB(17), 10)) + if (!values_close(c[1], MB(21), 10)) goto cleanup; if (c[3] != 0) @@ -417,9 +417,9 @@ static int test_memcg_min(const char *root) * * Then it checks actual memory usages and expects that: * A/B memory.current ~= 50M - * A/B/ memory.current ~= 33M - * A/B/D memory.current ~= 17M - * A/B/F memory.current ~= 0 + * A/B/ memory.current ~= 29M + * A/B/D memory.current ~= 21M + * A/B/E memory.current ~= 0 * * After that it tries to allocate more than there is * unprotected memory in A available, @@ -512,10 +512,10 @@ static int test_memcg_low(const char *root) for (i = 0; i < ARRAY_SIZE(children); i++) c[i] = cg_read_long(children[i], "memory.current"); - if (!values_close(c[0], MB(33), 10)) + if (!values_close(c[0], MB(29), 10)) goto cleanup; - if (!values_close(c[1], MB(17), 10)) + if (!values_close(c[1], MB(21), 10)) goto cleanup; if (c[3] != 0)
The numbers are not easy to derive in a closed form (certainly mere protections ratios do not apply), therefore use a simulation to obtain expected numbers. The new values make the protection tests succeed more precisely. % run as: octave-cli script % % Input configurations % ------------------- % E parent effective protection % n nominal protection of siblings set at the givel level % c current consumption -,,- % example from testcase (values in GB) E = 50 / 1024; n = [75 25 0 500 ] / 1024; c = [50 50 50 0] / 1024; % Reclaim parameters % ------------------ % Minimal reclaim amount (GB) cluster = 32*4 / 2**20; % Reclaim coefficient (think as 0.5^sc->priority) alpha = .1 % Simulation parameters % --------------------- epsilon = 1e-7; timeout = 1000; % Simulation loop % --------------------- % Simulation assumes siblings consumed the initial amount of memory (w/out % reclaim) and then the reclaim starts, all memory is reclaimable, i.e. treated % same. It simulates only non-low reclaim and assumes all memory.min = 0. ch = []; eh = []; rh = []; for t = 1:timeout % low_usage u = min(c, n); siblings = sum(u); % effective_protection() protected = min(n, c); % start with nominal e = protected * min(1, E / siblings); % normalize overcommit % recursive protection unclaimed = max(0, E - siblings); parent_overuse = sum(c) - siblings; if (unclaimed > 0 && parent_overuse > 0) overuse = max(0, c - protected); e += unclaimed * (overuse / parent_overuse); endif % get_scan_count() r = alpha * c; % assume all memory is in a single LRU list % commit 1bc63fb1272b ("mm, memcg: make scan aggression always exclude protection") sz = max(e, c); r .*= (1 - (e+epsilon) ./ (sz+epsilon)); % uncomment to debug prints % e, c, r % nothing to reclaim, reached equilibrium if max(r) < epsilon break; endif % SWAP_CLUSTER_MAX r = max(r, (r > epsilon) .* cluster); % XXX here I do parallel reclaim of all siblings % in reality reclaim is serialized and each sibling recalculates own residual c = max(c - r, 0); ch = [ch ; c]; eh = [eh ; e]; rh = [rh ; r]; endfor t c, e Signed-off-by: Michal Koutný <mkoutny@suse.com> --- .../selftests/cgroup/test_memcontrol.c | 20 +++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)