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git.proxmox.com Git - proxmox-backup.git/blob - pbs-tools/src/lib.rs
10 pub mod async_lru_cache
;
12 /// Set MMAP_THRESHOLD to a fixed value (128 KiB)
14 /// This avoids the "dynamic" mmap-treshold logic from glibc's malloc, which seems misguided and
15 /// effectively avoids using mmap for all allocations smaller than 32 MiB. Which, in combination
16 /// with the allocation pattern from our/tokio's complex async machinery, resulted in very large
17 /// RSS sizes due to defragmentation and long-living (smaller) allocation on top of the heap
18 /// avoiding that the (big) now free'd allocations below couldn't get given back to the OS. This is
19 /// not an issue with mmap'd memeory chunks, those can be given back at any time.
21 /// Lowering effective MMAP treshold to 128 KiB allows freeing up memory to the OS better and with
22 /// lower latency, which reduces the peak *and* average RSS size by an order of magnitude when
23 /// running backup jobs. We measured a reduction by a factor of 10-20 in experiments and see much
24 /// less erratic behavior in the overall's runtime RSS size.
25 pub fn setup_libc_malloc_opts() {
27 libc
::mallopt(libc
::M_MMAP_THRESHOLD
, 4096*32);