glibc's malloc has a misguided heuristic to detect transient allocations that
will just result in allocation sizes below 32 MiB never using mmap.
That it turn means that those relatively big allocations are on the heap where
cleanup and returning memory to the OS is harder to do and easier to be blocked
by long living, small allocations at the top (end) of the heap.
Observing the malloc size distribution in a file-level backup run:
@size:
[0] 14 | |
[1] 25214 |@@@@@ |
[2, 4) 9090 |@ |
[4, 8) 12987 |@@ |
[8, 16) 93453 |@@@@@@@@@@@@@@@@@@@@ |
[16, 32) 30255 |@@@@@@ |
[32, 64) 237445 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[64, 128) 32692 |@@@@@@@ |
[128, 256) 22296 |@@@@ |
[256, 512) 16177 |@@@ |
[512, 1K) 5139 |@ |
[1K, 2K) 3352 | |
[2K, 4K) 214 | |
[4K, 8K) 1568 | |
[8K, 16K) 95 | |
[16K, 32K) 3457 | |
[32K, 64K) 3175 | |
[64K, 128K) 161 | |
[128K, 256K) 453 | |
[256K, 512K) 93 | |
[512K, 1M) 74 | |
[1M, 2M) 774 | |
[2M, 4M) 319 | |
[4M, 8M) 700 | |
[8M, 16M) 93 | |
[16M, 32M) 18 | |
We see that all allocations will be on the heap, and that while most
allocations are small, the relatively few big ones will still make up most of
the RSS and if blocked from being released back to the OS result in much higher
peak and average usage for the program than actually required.
Avoiding the "dynamic" mmap-threshold increasement algorithm and fixing it at
the original default of 128 KiB reduces RSS size by factor 10-20 when running
backups. As with memory mappings other mappings or the heap can never block
freeing the memory fully back to the OS.
But, the drawback of using mmap is more wasted space for unaligned or small
allocation sizes, and the fact that the kernel allegedly zeros out the data
before giving it to user space. The former doesn't really matter for us when
using it only for allocations bigger than 128 KiB, and the latter is a
trade-off, using 10 to 20 times less memory brings its own performance
improvement possibilities for the whole system after all ;-)
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
[ Thomas: added to comment & commit message + extra-empty-line fixes ]
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
- imported pbs-api-types/src/common_regex.rs from old proxmox crate
- use hex crate to generate/parse hex digest
- remove all reference to proxmox crate (use proxmox-sys and
proxmox-serde instead)
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
Also moved pbs-datastore/src/crypt_config.rs to pbs-tools/src/crypt_config.rs.
We do not want to depend on pbs-api-types there, so I use [u8;32] instead of
Fingerprint.
This also moves a couple of required utilities such as
logrotate and some file descriptor methods to pbs-tools.
Note that the logrotate usage and run-dir handling should be
improved to work as a regular user as this *should* (IMHO)
be a regular unprivileged command (including running
qemu given the kvm privileges...)
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
pbs-datastore now ended up depending on tokio after all, but
that's fine for now
for the fuse code I added pbs-fuse-loop (has the old
fuse_loop and its 'loopdev' module)
ultimately only binaries should depend on this to avoid the
library link
the only thins remaining to move out the client binary are
the api method return types, those will need to be moved to
pbs-api-types...
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
