Messages in this thread | | | Subject | Re: [PATCH v2 3/3] mm/shuffle: remove dynamic reconfiguration | From | David Hildenbrand <> | Date | Mon, 22 Jun 2020 09:33:28 +0200 |
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On 20.06.20 03:49, Dan Williams wrote: > On Fri, Jun 19, 2020 at 5:59 AM David Hildenbrand <david@redhat.com> wrote: >> >> Commit e900a918b098 ("mm: shuffle initial free memory to improve >> memory-side-cache utilization") promised "autodetection of a >> memory-side-cache (to be added in a follow-on patch)" over a year ago. >> >> The original series included patches [1], however, they were dropped >> during review [2] to be followed-up later. >> >> Due to lack of platforms that publish an HMAT, autodetection is currently >> not implemented. However, manual activation is actively used [3]. Let's >> simplify for now and re-add when really (ever?) needed. >> >> [1] https://lkml.kernel.org/r/154510700291.1941238.817190985966612531.stgit@dwillia2-desk3.amr.corp.intel.com >> [2] https://lkml.kernel.org/r/154690326478.676627.103843791978176914.stgit@dwillia2-desk3.amr.corp.intel.com >> [3] https://lkml.kernel.org/r/CAPcyv4irwGUU2x+c6b4L=KbB1dnasNKaaZd6oSpYjL9kfsnROQ@mail.gmail.com >> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: Johannes Weiner <hannes@cmpxchg.org> >> Cc: Michal Hocko <mhocko@suse.com> >> Cc: Minchan Kim <minchan@kernel.org> >> Cc: Huang Ying <ying.huang@intel.com> >> Cc: Wei Yang <richard.weiyang@gmail.com> >> Cc: Mel Gorman <mgorman@techsingularity.net> >> Cc: Dan Williams <dan.j.williams@intel.com> >> Signed-off-by: David Hildenbrand <david@redhat.com> >> --- >> mm/shuffle.c | 28 ++-------------------------- >> mm/shuffle.h | 17 ----------------- >> 2 files changed, 2 insertions(+), 43 deletions(-) >> >> diff --git a/mm/shuffle.c b/mm/shuffle.c >> index dd13ab851b3ee..9b5cd4b004b0f 100644 >> --- a/mm/shuffle.c >> +++ b/mm/shuffle.c >> @@ -10,33 +10,11 @@ >> #include "shuffle.h" >> >> DEFINE_STATIC_KEY_FALSE(page_alloc_shuffle_key); >> -static unsigned long shuffle_state __ro_after_init; >> - >> -/* >> - * Depending on the architecture, module parameter parsing may run >> - * before, or after the cache detection. SHUFFLE_FORCE_DISABLE prevents, >> - * or reverts the enabling of the shuffle implementation. SHUFFLE_ENABLE >> - * attempts to turn on the implementation, but aborts if it finds >> - * SHUFFLE_FORCE_DISABLE already set. >> - */ >> -__meminit void page_alloc_shuffle(enum mm_shuffle_ctl ctl) >> -{ >> - if (ctl == SHUFFLE_FORCE_DISABLE) >> - set_bit(SHUFFLE_FORCE_DISABLE, &shuffle_state); >> - >> - if (test_bit(SHUFFLE_FORCE_DISABLE, &shuffle_state)) { >> - if (test_and_clear_bit(SHUFFLE_ENABLE, &shuffle_state)) >> - static_branch_disable(&page_alloc_shuffle_key); >> - } else if (ctl == SHUFFLE_ENABLE >> - && !test_and_set_bit(SHUFFLE_ENABLE, &shuffle_state)) >> - static_branch_enable(&page_alloc_shuffle_key); >> -} >> >> static bool shuffle_param; >> static int shuffle_show(char *buffer, const struct kernel_param *kp) >> { >> - return sprintf(buffer, "%c\n", test_bit(SHUFFLE_ENABLE, &shuffle_state) >> - ? 'Y' : 'N'); >> + return sprintf(buffer, "%c\n", shuffle_param ? 'Y' : 'N'); >> } >> >> static __meminit int shuffle_store(const char *val, >> @@ -47,9 +25,7 @@ static __meminit int shuffle_store(const char *val, >> if (rc < 0) >> return rc; >> if (shuffle_param) >> - page_alloc_shuffle(SHUFFLE_ENABLE); >> - else >> - page_alloc_shuffle(SHUFFLE_FORCE_DISABLE); >> + static_branch_enable(&page_alloc_shuffle_key); >> return 0; >> } > > Let's do proper input validation here and require 1 / 'true' to enable > shuffling and not also allow 0 to be an 'enable' value.
I don't think that's currently done?
param_set_bool(val, kp) will only default val==NULL to 'true'. Passing 0 will properly be handled by strtobool(). Or am I missing something?
Thanks!
-- Thanks,
David / dhildenb
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