>how to not OOM while protecting too many buffers...
A workaround for a production 2.2.x is:
echo 4 >/proc/sys/vm/bdflush
The right fix should looks like the below patch:
--- 2.3.35pre4-ramdisk-oom/fs/buffer.c.~1~ Fri Dec 24 02:00:56 1999
+++ 2.3.35pre4-ramdisk-oom/fs/buffer.c Mon Dec 27 00:24:37 1999
@@ -818,7 +818,8 @@
{
unsigned long dirty, tot, hard_dirty_limit, soft_dirty_limit;
- dirty = size_buffers_type[BUF_DIRTY] >> PAGE_SHIFT;
+ dirty = size_buffers_type[BUF_DIRTY]+size_buffers_type[BUF_PROTECTED];
+ dirty >>= PAGE_SHIFT;
tot = nr_free_buffer_pages();
hard_dirty_limit = tot * bdf_prm.b_un.nfract / 100;
soft_dirty_limit = hard_dirty_limit >> 1;
@@ -871,6 +872,8 @@
dispose = BUF_LOCKED;
if (buffer_dirty(bh))
dispose = BUF_DIRTY;
+ if (buffer_protected(bh))
+ dispose = BUF_PROTECTED;
if (dispose != bh->b_list) {
__remove_from_lru_list(bh, bh->b_list);
bh->b_list = dispose;
@@ -2071,7 +2074,7 @@
int found = 0, locked = 0, dirty = 0, used = 0, lastused = 0;
int protected = 0;
int nlist;
- static char *buf_types[NR_LIST] = { "CLEAN", "LOCKED", "DIRTY" };
+ static char *buf_types[NR_LIST] = { "CLEAN", "LOCKED", "DIRTY", "PROTECTED", };
#endif
printk("Buffer memory: %6dkB\n",
--- 2.3.35pre4-ramdisk-oom/include/linux/fs.h.~1~ Fri Dec 24 02:20:17 1999
+++ 2.3.35pre4-ramdisk-oom/include/linux/fs.h Mon Dec 27 00:19:11 1999
@@ -788,7 +788,8 @@
#define BUF_CLEAN 0
#define BUF_LOCKED 1 /* Buffers scheduled for write */
#define BUF_DIRTY 2 /* Dirty buffers, not yet scheduled for write */
-#define NR_LIST 3
+#define BUF_PROTECTED 3 /* Ramdisk persistent storage */
+#define NR_LIST 4
/*
* This is called by bh->b_end_io() handlers when I/O has completed.
Andrea
-
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