The patch titled
knfsd: nfsd4: vary maximum delegation limit based on RAM size
has been removed from the -mm tree. Its filename was
knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: knfsd: nfsd4: vary maximum delegation limit based on RAM size
From: Meelap Shah <meelap@xxxxxxxxx>
Our original NFSv4 delegation policy was to give out a read delegation on any
open when it was possible to.
Since the lifetime of a delegation isn't limited to that of an open, a client
may quite reasonably hang on to a delegation as long as it has the inode
cached. This becomes an obvious problem the first time a client's inode cache
approaches the size of the server's total memory.
Our first quick solution was to add a hard-coded limit. This patch makes a
mild incremental improvement by varying that limit according to the server's
total memory size, allowing at most 4 delegations per megabyte of RAM.
My quick back-of-the-envelope calculation finds that in the worst case (where
every delegation is for a different inode), a delegation could take about
1.5K, which would make the worst case usage about 6% of memory. The new limit
works out to be about the same as the old on a 1-gig server.
[akpm@xxxxxxxxxxxxxxxxxxxx: Don't needlessly bloat vmlinux]
[akpm@xxxxxxxxxxxxxxxxxxxx: Make it right for highmem machines]
Signed-off-by: "J. Bruce Fields" <bfields@xxxxxxxxxxxxxx>
Signed-off-by: Neil Brown <neilb@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nfsd/nfs4state.c | 26 +++++++++++++++++++++++++-
include/linux/nfsd/nfsd.h | 1 +
mm/page_alloc.c | 1 +
3 files changed, 27 insertions(+), 1 deletion(-)
diff -puN fs/nfsd/nfs4state.c~knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size fs/nfsd/nfs4state.c
--- a/fs/nfsd/nfs4state.c~knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size
+++ a/fs/nfsd/nfs4state.c
@@ -49,6 +49,7 @@
#include <linux/nfsd/state.h>
#include <linux/nfsd/xdr4.h>
#include <linux/namei.h>
+#include <linux/swap.h>
#include <linux/mutex.h>
#include <linux/lockd/bind.h>
#include <linux/module.h>
@@ -150,6 +151,7 @@ get_nfs4_file(struct nfs4_file *fi)
}
static int num_delegations;
+unsigned int max_delegations;
/*
* Open owner state (share locks)
@@ -193,7 +195,7 @@ alloc_init_deleg(struct nfs4_client *clp
struct nfs4_callback *cb = &stp->st_stateowner->so_client->cl_callback;
dprintk("NFSD alloc_init_deleg\n");
- if (num_delegations > STATEID_HASH_SIZE * 4)
+ if (num_delegations > max_delegations)
return NULL;
dp = kmem_cache_alloc(deleg_slab, GFP_KERNEL);
if (dp == NULL)
@@ -3197,6 +3199,27 @@ get_nfs4_grace_period(void)
return max(user_lease_time, lease_time) * HZ;
}
+/*
+ * Since the lifetime of a delegation isn't limited to that of an open, a
+ * client may quite reasonably hang on to a delegation as long as it has
+ * the inode cached. This becomes an obvious problem the first time a
+ * client's inode cache approaches the size of the server's total memory.
+ *
+ * For now we avoid this problem by imposing a hard limit on the number
+ * of delegations, which varies according to the server's memory size.
+ */
+static void
+set_max_delegations(void)
+{
+ /*
+ * Allow at most 4 delegations per megabyte of RAM. Quick
+ * estimates suggest that in the worst case (where every delegation
+ * is for a different inode), a delegation could take about 1.5K,
+ * giving a worst case usage of about 6% of memory.
+ */
+ max_delegations = nr_free_buffer_pages() >> (20 - 2 - PAGE_SHIFT);
+}
+
/* initialization to perform when the nfsd service is started: */
static void
@@ -3212,6 +3235,7 @@ __nfs4_state_start(void)
grace_time/HZ);
laundry_wq = create_singlethread_workqueue("nfsd4");
queue_delayed_work(laundry_wq, &laundromat_work, grace_time);
+ set_max_delegations();
}
int
diff -puN include/linux/nfsd/nfsd.h~knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size include/linux/nfsd/nfsd.h
--- a/include/linux/nfsd/nfsd.h~knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size
+++ a/include/linux/nfsd/nfsd.h
@@ -148,6 +148,7 @@ extern int nfsd_max_blksize;
* NFSv4 State
*/
#ifdef CONFIG_NFSD_V4
+extern unsigned int max_delegations;
void nfs4_state_init(void);
int nfs4_state_start(void);
void nfs4_state_shutdown(void);
diff -puN mm/page_alloc.c~knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size mm/page_alloc.c
--- a/mm/page_alloc.c~knfsd-nfsd4-vary-maximum-delegation-limit-based-on-ram-size
+++ a/mm/page_alloc.c
@@ -1484,6 +1484,7 @@ unsigned int nr_free_buffer_pages(void)
{
return nr_free_zone_pages(gfp_zone(GFP_USER));
}
+EXPORT_SYMBOL_GPL(nr_free_buffer_pages);
/*
* Amount of free RAM allocatable within all zones
_
Patches currently in -mm which might be from meelap@xxxxxxxxx are
origin.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
