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=== Description (from pull-request) ===
Signed-off-by: Dieter Maier <d...@web.de>
It concerns the combination of a system with activated swap and docker. When I use lxcfs to limit the memory resources of a container, I always have swap.. Which I don't want.
docker run -it -m 256m --memory-swap 256m \
-v /var/lib/lxcfs/proc/cpuinfo:/proc/cpuinfo:rw \
-v /var/lib/lxcfs/proc/diskstats:/proc/diskstats:rw \
-v /var/lib/lxcfs/proc/meminfo:/proc/meminfo:rw \
-v /var/lib/lxcfs/proc/stat:/proc/stat:rw \
-v /var/lib/lxcfs/proc/swaps:/proc/swaps:rw \
-v /var/lib/lxcfs/proc/uptime:/proc/uptime:rw \
ubuntu:18.04 /bin/bash
That, too, is not satisfactory:
docker run -it -m 256m \
-v /var/lib/lxcfs/proc/cpuinfo:/proc/cpuinfo:rw \
....
I can force with the parameter "-u" that the swap values in the "meminfo" are always 0.
To use this parameter I use "fuse_get_context()->private_data".
It is a very special use case, but I wanted to at least suggest it.
I haven't programmed a C for a long time, so please take a critical look at it.
It works very well with Ubuntu. Unfortunately not with Alpine yet. I tested it with "free".
I developed the customization to use several mongodb on one docker host, which unfortunately have swap enabled. This works very well.
From fe2549f18f95abd42bf412887e595a5de675f3e0 Mon Sep 17 00:00:00 2001
From: dm <dm@localhost>
Date: Mon, 18 Feb 2019 06:17:30 +0100
Subject: [PATCH] option to disable swap in meminfo
Signed-off-by: Dieter Maier <d...@web.de>
---
README.md | 17 +++++++++++++++++
bindings.c | 35 +++++++++++++++++++++++++----------
bindings.h | 4 ++++
lxcfs.c | 20 ++++++++++++++++----
4 files changed, 62 insertions(+), 14 deletions(-)
diff --git a/README.md b/README.md
index 4c1434a..93e7b37 100644
--- a/README.md
+++ b/README.md
@@ -60,3 +60,20 @@ send `SIGUSR1` to the pid of the running `LXCFS` process.
This can be as simple
as doing:
kill -s USR1 $(pidof lxcfs)
+
+## Using with Docker
+
+```
+docker run -it -m 256m --memory-swap 256m \
+ -v /var/lib/lxcfs/proc/cpuinfo:/proc/cpuinfo:rw \
+ -v /var/lib/lxcfs/proc/diskstats:/proc/diskstats:rw \
+ -v /var/lib/lxcfs/proc/meminfo:/proc/meminfo:rw \
+ -v /var/lib/lxcfs/proc/stat:/proc/stat:rw \
+ -v /var/lib/lxcfs/proc/swaps:/proc/swaps:rw \
+ -v /var/lib/lxcfs/proc/uptime:/proc/uptime:rw \
+ ubuntu:18.04 /bin/bash
+ ```
+
+ In a system with swap enabled, the parameter "-n" can be used to set all
values in "meminfo" that refer to the swap to 0.
+
+ sudo lxcfs -u /var/lib/lxcfs
diff --git a/bindings.c b/bindings.c
index 097ca81..a90f349 100644
--- a/bindings.c
+++ b/bindings.c
@@ -3437,6 +3437,7 @@ static int proc_meminfo_read(char *buf, size_t size,
off_t offset,
struct fuse_file_info *fi)
{
struct fuse_context *fc = fuse_get_context();
+ struct lxcfs_opts *opts = (struct lxcfs_opts *)
fuse_get_context()->private_data;
struct file_info *d = (struct file_info *)fi->fh;
char *cg;
char *memusage_str = NULL, *memstat_str = NULL,
@@ -3517,18 +3518,32 @@ static int proc_meminfo_read(char *buf, size_t size,
off_t offset,
} else if (startswith(line, "MemAvailable:")) {
snprintf(lbuf, 100, "MemAvailable: %8lu kB\n",
memlimit - memusage + cached);
printme = lbuf;
- } else if (startswith(line, "SwapTotal:") && memswlimit > 0) {
- sscanf(line+sizeof("SwapTotal:")-1, "%lu",
&hostswtotal);
- if (hostswtotal < memswlimit)
- memswlimit = hostswtotal;
- snprintf(lbuf, 100, "SwapTotal: %8lu kB\n",
memswlimit);
- printme = lbuf;
- } else if (startswith(line, "SwapFree:") && memswlimit > 0 &&
memswusage > 0) {
- unsigned long swaptotal = memswlimit,
+ } else if (startswith(line, "SwapTotal:")) {
+ if (memswlimit > 0) {
+ sscanf(line+sizeof("SwapTotal:")-1, "%lu",
&hostswtotal);
+ if (hostswtotal < memswlimit)
+ memswlimit = hostswtotal;
+ snprintf(lbuf, 100, "SwapTotal: %8lu kB\n",
memswlimit);
+ printme = lbuf;
+ }
+ if (opts->swap_off == true) {
+ memswlimit = 0;
+ snprintf(lbuf, 100, "SwapTotal: %8lu kB\n",
memswlimit);
+ printme = lbuf;
+ }
+ } else if (startswith(line, "SwapFree:")) {
+ if (memswlimit > 0 && memswusage > 0) {
+ unsigned long swaptotal = memswlimit,
swapusage = memswusage - memusage,
swapfree = swapusage < swaptotal ?
swaptotal - swapusage : 0;
- snprintf(lbuf, 100, "SwapFree: %8lu kB\n",
swapfree);
- printme = lbuf;
+ snprintf(lbuf, 100, "SwapFree: %8lu kB\n",
swapfree);
+ printme = lbuf;
+ }
+ if (opts->swap_off == true) {
+ unsigned long swapfree = 0;
+ snprintf(lbuf, 100, "SwapFree: %8lu kB\n",
swapfree);
+ printme = lbuf;
+ }
} else if (startswith(line, "Slab:")) {
snprintf(lbuf, 100, "Slab: %8lu kB\n", 0UL);
printme = lbuf;
diff --git a/bindings.h b/bindings.h
index f1a4627..2f76861 100644
--- a/bindings.h
+++ b/bindings.h
@@ -7,6 +7,10 @@
#define BASEDIR RUNTIME_PATH "/lxcfs/controllers"
#define ROOTDIR RUNTIME_PATH "/lxcfs/root"
+struct lxcfs_opts {
+ bool swap_off;
+};
+
extern int cg_write(const char *path, const char *buf, size_t size, off_t
offset,
struct fuse_file_info *fi);
extern int cg_mkdir(const char *path, mode_t mode);
diff --git a/lxcfs.c b/lxcfs.c
index 76b3ea2..953266b 100644
--- a/lxcfs.c
+++ b/lxcfs.c
@@ -792,9 +792,10 @@ static void usage()
{
fprintf(stderr, "Usage:\n");
fprintf(stderr, "\n");
- fprintf(stderr, "lxcfs [-f|-d] -l [-p pidfile] mountpoint\n");
+ fprintf(stderr, "lxcfs [-f|-d] -u -l -n [-p pidfile] mountpoint\n");
fprintf(stderr, " -f running foreground by default; -d enable debug
output \n");
fprintf(stderr, " -l use loadavg \n");
+ fprintf(stderr, " -u no swap \n");
fprintf(stderr, " Default pidfile is %s/lxcfs.pid\n", RUNTIME_PATH);
fprintf(stderr, "lxcfs -h\n");
exit(1);
@@ -903,7 +904,15 @@ int main(int argc, char *argv[])
*/
int nargs = 5, cnt = 0;
char *newargv[6];
-
+
+ struct lxcfs_opts *opts;
+ opts = malloc(sizeof(struct lxcfs_opts));
+ if (opts == NULL) {
+ fprintf(stderr, "Error setting options: %m\n");
+ goto out;
+ }
+ opts->swap_off = false;
+
/* accomodate older init scripts */
swallow_arg(&argc, argv, "-s");
swallow_arg(&argc, argv, "-f");
@@ -911,6 +920,9 @@ int main(int argc, char *argv[])
if (swallow_arg(&argc, argv, "-l")) {
load_use = true;
}
+ if (swallow_arg(&argc, argv, "-u")) {
+ opts->swap_off = true;
+ }
if (swallow_option(&argc, argv, "-o", &v)) {
/* Parse multiple values */
for (; (token = strtok_r(v, ",", &saveptr)); v = NULL) {
@@ -929,7 +941,7 @@ int main(int argc, char *argv[])
}
if (swallow_option(&argc, argv, "-p", &v))
pidfile = v;
-
+
if (argc == 2 && strcmp(argv[1], "--version") == 0) {
fprintf(stderr, "%s\n", VERSION);
exit(EXIT_SUCCESS);
@@ -967,7 +979,7 @@ int main(int argc, char *argv[])
if (load_use && start_loadavg() != 0)
goto out;
- if (!fuse_main(nargs, newargv, &lxcfs_ops, NULL))
+ if (!fuse_main(nargs, newargv, &lxcfs_ops, opts))
ret = EXIT_SUCCESS;
if (load_use)
stop_loadavg();
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