| Message ID | tencent_DFF54DB2A60F3333F97D3F6B5441519B050A@qq.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm: compaction: optimize compact_memory to comply with the admin-guide | expand |
On Tue, Apr 25, 2023 at 11:52:35PM +0800, wenyang.linux@foxmail.com wrote: > From: Wen Yang <wenyang.linux@foxmail.com> > > For the /proc/sys/vm/compact_memory file, the admin-guide states: > When 1 is written to the file, all zones are compacted such that free > memory is available in contiguous blocks where possible. This can be > important for example in the allocation of huge pages although processes > will also directly compact memory as required > > But it was not strictly followed, writing any value would cause all > zones to be compacted. > It has been slightly optimized to comply with the admin-guide. > Enforce the 1 on the unlikely chance that the sysctl handler is ever > extended to do something different. > > Commit ef4984384172 ("mm/compaction: remove unused variable sysctl_compact_memory") > has also been optimized a bit here, as the declaration in the external header > file has been eliminated, and sysctl_compact_memory also needs to be verified. > > Signed-off-by: Wen Yang <wenyang.linux@foxmail.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Oscar Salvador <osalvador@suse.de> > Cc: William Lam <william.lam@bytedance.com> > Cc: Pintu Kumar <pintu@codeaurora.org> > Cc: Fu Wei <wefu@redhat.com> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/compaction.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index c8bcdea15f5f..ba57d4178866 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -1736,6 +1736,7 @@ static int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNE > */ > static unsigned int __read_mostly sysctl_compaction_proactiveness = 20; > static int sysctl_extfrag_threshold = 500; > +static int sysctl_compact_memory; > __read_mostly but that aside, it's only used in sysctl_compaction_handler so could also be declared as static within that function. That way if CONFIG_SYSCTL is not set, it should be guaranteed that the compiler does not save storage for it. It's minor enough that With or without another version; Acked-by: Mel Gorman <mgorman@techsingularity.net>
On Fri, 28 Apr 2023 11:58:48 +0100 Mel Gorman <mgorman@techsingularity.net> wrote: > > --- a/mm/compaction.c > > +++ b/mm/compaction.c > > @@ -1736,6 +1736,7 @@ static int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNE > > */ > > static unsigned int __read_mostly sysctl_compaction_proactiveness = 20; > > static int sysctl_extfrag_threshold = 500; > > +static int sysctl_compact_memory; > > > > __read_mostly but that aside, it's only used in > sysctl_compaction_handler so could also be declared as static within > that function. That way if CONFIG_SYSCTL is not set, it should be > guaranteed that the compiler does not save storage for it. but static struct ctl_table vm_compaction[] = { { .procname = "compact_memory", .data = &sysctl_compact_memory, .maxlen = sizeof(int), .mode = 0200, .proc_handler = sysctl_compaction_handler, }, I'll add the __read_mostly, thanks.
diff --git a/mm/compaction.c b/mm/compaction.c index c8bcdea15f5f..ba57d4178866 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1736,6 +1736,7 @@ static int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNE */ static unsigned int __read_mostly sysctl_compaction_proactiveness = 20; static int sysctl_extfrag_threshold = 500; +static int sysctl_compact_memory; static inline void update_fast_start_pfn(struct compact_control *cc, unsigned long pfn) @@ -2780,6 +2781,15 @@ static int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int static int sysctl_compaction_handler(struct ctl_table *table, int write, void *buffer, size_t *length, loff_t *ppos) { + int ret; + + ret = proc_dointvec(table, write, buffer, length, ppos); + if (ret) + return ret; + + if (sysctl_compact_memory != 1) + return -EINVAL; + if (write) compact_nodes(); @@ -3095,7 +3105,7 @@ static int proc_dointvec_minmax_warn_RT_change(struct ctl_table *table, static struct ctl_table vm_compaction[] = { { .procname = "compact_memory", - .data = NULL, + .data = &sysctl_compact_memory, .maxlen = sizeof(int), .mode = 0200, .proc_handler = sysctl_compaction_handler,