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writecache: check memory usage

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warn if writecache neds > 50% of system memory, and
confirm if writecache needs > 90% of system memory.
This commit is contained in:
David Teigland 2022-03-01 14:31:39 -06:00
parent cc73d99886
commit bef1363c00
1 changed files with 69 additions and 0 deletions
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69
tools/lvconvert.c
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@ -6070,6 +6070,69 @@ bad:
return 0;
}
static int _check_writecache_memory(struct cmd_context *cmd, struct logical_volume *lv_fast,
uint32_t block_size_sectors)
{
char line[128];
FILE *fp;
uint64_t cachevol_size_bytes = lv_fast->size * SECTOR_SIZE;
uint64_t need_mem_bytes = 0;
uint64_t proc_mem_bytes = 0;
uint64_t need_mem_gb;
uint64_t proc_mem_gb;
unsigned long long proc_mem_kb = 0;
if (!(fp = fopen("/proc/meminfo", "r")))
goto skip_proc;
while (fgets(line, sizeof(line), fp)) {
if (strncmp(line, "MemTotal:", 9))
continue;
if (sscanf(line, "%*s%llu%*s", &proc_mem_kb) != 1)
break;
break;
}
(void)fclose(fp);
proc_mem_bytes = proc_mem_kb * 1024;
skip_proc:
/* dm-writecache memory consumption per block is 88 bytes */
if (block_size_sectors == 8) {
need_mem_bytes = cachevol_size_bytes * 88 / 4096;
} else if (block_size_sectors == 1) {
need_mem_bytes = cachevol_size_bytes * 88 / 512;
} else {
/* shouldn't happen */
log_warn("Unknown memory usage for unknown writecache block_size_sectors %u", block_size_sectors);
return 1;
}
need_mem_gb = need_mem_bytes / 1073741824;
proc_mem_gb = proc_mem_bytes / 1073741824;
/*
* warn if writecache needs > 50% of main memory, and
* confirm if writecache needs > 90% of main memory.
*/
if (need_mem_bytes >= (proc_mem_bytes / 2)) {
log_warn("WARNING: writecache size %s will use %llu GiB of system memory (%llu GiB).",
display_size(cmd, lv_fast->size),
(unsigned long long)need_mem_gb,
(unsigned long long)proc_mem_gb);
if (need_mem_gb >= (proc_mem_gb * 9 / 10)) {
if (!arg_is_set(cmd, yes_ARG) &&
yes_no_prompt("Continue adding writecache? [y/n]: ") == 'n') {
log_error("Conversion aborted.");
return 0;
}
}
}
return 1;
}
int lvconvert_writecache_attach_single(struct cmd_context *cmd,
struct logical_volume *lv,
struct processing_handle *handle)
@ -6158,6 +6221,12 @@ int lvconvert_writecache_attach_single(struct cmd_context *cmd,
goto_bad;
}
if (!_check_writecache_memory(cmd, lv_fast, block_size_sectors)) {
if (!is_active && !deactivate_lv(cmd, lv))
stack;
goto_bad;
}
if (!is_active) {
if (!deactivate_lv(cmd, lv)) {
log_error("Failed to deactivate LV after checking block size %s", display_lvname(lv));