__vm_enough_memory reserves a hardcoded 3% of free memory for other processes
when overcommit is disabled. However, 3% is becoming excessive as memory sizes
increase and memory cgroups provide a more flexible way to manage the issue
anyway.
This patch against 3.8 removes the "other" reserve.
I've found that reducing this reserve is beneficial in the case where a system
with overcommit disabled has one primary user that wants to allocate as much
memory as possible with a just few processes.
An additional hardcoded 3% is reserved for root, both when overcommit is
enabled
and when it is disabled. I've made it tunable in private patches, and I plan on
submitting some version of them, but I can't decide whether a ratio or a byte
count would be more acceptable. What would people prefer see?
Signed-off-by: Andrew Shewmaker <ags...@gmail.com>
diff --git a/mm/mmap.c b/mm/mmap.c
index 09da0b2..eef9505 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -183,11 +183,6 @@ int __vm_enough_memory(struct mm_struct *mm, long pages,
int cap_sys_admin)
allowed -= allowed / 32;
allowed += total_swap_pages;
- /* Don't let a single process grow too big:
- leave 3% of the size of this process for other processes */
- if (mm)
- allowed -= mm->total_vm / 32;
-
if (percpu_counter_read_positive(&vm_committed_as) < allowed)
return 0;
error:
--
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