Hook up networking to the memory reserve.
There are two kinds of reserves: skb and aux.
- skb reserves are used for incomming packets,
- aux reserves are used for processing these packets.
The consumers for these reserves are sockets marked with:
SOCK_VMIO
Such sockets are to be used to service the VM (iow. to swap over). They
must be handled kernel side, exposing such a socket to user-space is a BUG.
Signed-off-by: Peter Zijlstra <[email protected]>
---
include/net/sock.h | 43 ++++++++++++++++
net/Kconfig | 3 +
net/core/sock.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 180 insertions(+), 1 deletion(-)
Index: linux-2.6-git/include/net/sock.h
===================================================================
--- linux-2.6-git.orig/include/net/sock.h
+++ linux-2.6-git/include/net/sock.h
@@ -49,6 +49,7 @@
#include <linux/skbuff.h> /* struct sk_buff */
#include <linux/mm.h>
#include <linux/security.h>
+#include <linux/log2.h>
#include <linux/filter.h>
@@ -393,6 +394,7 @@ enum sock_flags {
SOCK_RCVTSTAMPNS, /* %SO_TIMESTAMPNS setting */
SOCK_LOCALROUTE, /* route locally only, %SO_DONTROUTE setting */
SOCK_QUEUE_SHRUNK, /* write queue has been shrunk recently */
+ SOCK_VMIO, /* the VM depends on us - make sure we're serviced */
};
static inline void sock_copy_flags(struct sock *nsk, struct sock *osk)
@@ -415,9 +417,48 @@ static inline int sock_flag(struct sock
return test_bit(flag, &sk->sk_flags);
}
+static inline int sk_has_vmio(struct sock *sk)
+{
+ return sock_flag(sk, SOCK_VMIO);
+}
+
+/*
+ * Guestimate the per request queue TX upper bound.
+ *
+ * Max packet size is 64k, and we need to reserve that much since the data
+ * might need to bounce it. Double it to be on the safe side.
+ */
+#define TX_RESERVE_PAGES DIV_ROUND_UP(2*65536, PAGE_SIZE)
+
+extern atomic_t vmio_socks;
+
+static inline int sk_vmio_socks(void)
+{
+ return atomic_read(&vmio_socks);
+}
+
+extern int rx_emergency_get(int bytes);
+extern int rx_emergency_get_overcommit(int bytes);
+extern void rx_emergency_put(int bytes);
+
+static inline
+int guess_kmem_cache_pages(struct kmem_cache *cachep, int nr_objs)
+{
+ int guess = DIV_ROUND_UP((kmem_cache_objsize(cachep) * nr_objs),
+ PAGE_SIZE);
+ guess += ilog2(guess);
+ return guess;
+}
+
+extern void sk_adjust_memalloc(int socks, int tx_reserve_pages);
+extern void skb_reserve_memory(int skb_reserve_bytes);
+extern void aux_reserve_memory(int aux_reserve_pages);
+extern int sk_set_vmio(struct sock *sk);
+extern int sk_clear_vmio(struct sock *sk);
+
static inline gfp_t sk_allocation(struct sock *sk, gfp_t gfp_mask)
{
- return gfp_mask;
+ return gfp_mask | (sk->sk_allocation & __GFP_EMERGENCY);
}
static inline void sk_acceptq_removed(struct sock *sk)
Index: linux-2.6-git/net/core/sock.c
===================================================================
--- linux-2.6-git.orig/net/core/sock.c
+++ linux-2.6-git/net/core/sock.c
@@ -112,6 +112,7 @@
#include <linux/tcp.h>
#include <linux/init.h>
#include <linux/highmem.h>
+#include <linux/log2.h>
#include <asm/uaccess.h>
#include <asm/system.h>
@@ -198,6 +199,139 @@ __u32 sysctl_rmem_default __read_mostly
/* Maximal space eaten by iovec or ancilliary data plus some space */
int sysctl_optmem_max __read_mostly = sizeof(unsigned long)*(2*UIO_MAXIOV+512);
+static atomic_t rx_emergency_bytes;
+
+static int skb_reserve_bytes;
+static int aux_reserve_pages;
+
+static DEFINE_SPINLOCK(memalloc_lock);
+static int rx_net_reserve;
+atomic_t vmio_socks;
+EXPORT_SYMBOL_GPL(vmio_socks);
+
+/*
+ * is there room for another emergency packet?
+ * we account in power of two units to approx the slab allocator.
+ */
+static int __rx_emergency_get(int bytes, bool overcommit)
+{
+ int size = roundup_pow_of_two(bytes);
+ int nr = atomic_add_return(size, &rx_emergency_bytes);
+ int thresh = 2 * skb_reserve_bytes;
+ if (nr < thresh || overcommit)
+ return 1;
+
+ atomic_dec(&rx_emergency_bytes);
+ return 0;
+}
+
+int rx_emergency_get(int bytes)
+{
+ return __rx_emergency_get(bytes, false);
+}
+
+int rx_emergency_get_overcommit(int bytes)
+{
+ return __rx_emergency_get(bytes, true);
+}
+
+void rx_emergency_put(int bytes)
+{
+ int size = roundup_pow_of_two(bytes);
+ return atomic_sub(size, &rx_emergency_bytes);
+}
+
+/**
+ * sk_adjust_memalloc - adjust the global memalloc reserve for critical RX
+ * @socks: number of new %SOCK_VMIO sockets
+ * @tx_resserve_pages: number of pages to (un)reserve for TX
+ *
+ * This function adjusts the memalloc reserve based on system demand.
+ * The RX reserve is a limit, and only added once, not for each socket.
+ *
+ * NOTE:
+ * @tx_reserve_pages is an upper-bound of memory used for TX hence
+ * we need not account the pages like we do for RX pages.
+ */
+void sk_adjust_memalloc(int socks, int tx_reserve_pages)
+{
+ unsigned long flags;
+ int reserve = tx_reserve_pages;
+ int nr_socks;
+
+ spin_lock_irqsave(&memalloc_lock, flags);
+ nr_socks = atomic_add_return(socks, &vmio_socks);
+ BUG_ON(nr_socks < 0);
+
+ if (nr_socks) {
+ int skb_reserve_pages =
+ DIV_ROUND_UP(skb_reserve_bytes, PAGE_SIZE);
+ int rx_pages = 2 * skb_reserve_pages + aux_reserve_pages;
+ reserve += rx_pages - rx_net_reserve;
+ rx_net_reserve = rx_pages;
+ } else {
+ reserve -= rx_net_reserve;
+ rx_net_reserve = 0;
+ }
+
+ if (reserve)
+ adjust_memalloc_reserve(reserve);
+ spin_unlock_irqrestore(&memalloc_lock, flags);
+}
+EXPORT_SYMBOL_GPL(sk_adjust_memalloc);
+
+/*
+ * tiny helper functions to track the memory reserves
+ * needed because of modular ipv6
+ */
+void skb_reserve_memory(int bytes)
+{
+ skb_reserve_bytes += bytes;
+ sk_adjust_memalloc(0, 0);
+}
+EXPORT_SYMBOL_GPL(skb_reserve_memory);
+
+void aux_reserve_memory(int pages)
+{
+ aux_reserve_pages += pages;
+ sk_adjust_memalloc(0, 0);
+}
+EXPORT_SYMBOL_GPL(aux_reserve_memory);
+
+/**
+ * sk_set_vmio - sets %SOCK_VMIO
+ * @sk: socket to set it on
+ *
+ * Set %SOCK_VMIO on a socket and increase the memalloc reserve
+ * accordingly.
+ */
+int sk_set_vmio(struct sock *sk)
+{
+ int set = sock_flag(sk, SOCK_VMIO);
+#ifndef CONFIG_NETVM
+ BUG();
+#endif
+ if (!set) {
+ sk_adjust_memalloc(1, 0);
+ sock_set_flag(sk, SOCK_VMIO);
+ sk->sk_allocation |= __GFP_EMERGENCY;
+ }
+ return !set;
+}
+EXPORT_SYMBOL_GPL(sk_set_vmio);
+
+int sk_clear_vmio(struct sock *sk)
+{
+ int set = sock_flag(sk, SOCK_VMIO);
+ if (set) {
+ sk_adjust_memalloc(-1, 0);
+ sock_reset_flag(sk, SOCK_VMIO);
+ sk->sk_allocation &= ~__GFP_EMERGENCY;
+ }
+ return set;
+}
+EXPORT_SYMBOL_GPL(sk_clear_vmio);
+
static int sock_set_timeout(long *timeo_p, char __user *optval, int optlen)
{
struct timeval tv;
@@ -879,6 +1013,7 @@ void sk_free(struct sock *sk)
struct sk_filter *filter;
struct module *owner = sk->sk_prot_creator->owner;
+ sk_clear_vmio(sk);
if (sk->sk_destruct)
sk->sk_destruct(sk);
Index: linux-2.6-git/net/Kconfig
===================================================================
--- linux-2.6-git.orig/net/Kconfig
+++ linux-2.6-git/net/Kconfig
@@ -224,6 +224,9 @@ source "net/ieee80211/Kconfig"
endmenu
+config NETVM
+ def_bool n
+
endif # if NET
endmenu # Networking
--
-
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