As soon as skb is pushed to hardware, it can be completed and freed, so
we should not dereference skb anymore.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We need rcu_read_lock() protection before using dst_get_neighbour(), and
we must cache its value (pass it to __teql_resolve())
teql_master_xmit() is called under rcu_read_lock_bh() protection, its
not enough.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changes to bnx2 to use byte queue limits.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Since commit 230dec6 (net/fec: add imx6q enet support) the FEC driver is no
longer built by default for i.MX SoCs.
Let the FEC driver be built by default again.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Rick Jones reported that TCP_CONGESTION sockopt performed on a listener
was ignored for its children sockets : right after accept() the
congestion control for new socket is the system default one.
This seems an oversight of the initial design (quoted from Stephen)
Based on prior investigation and patch from Rick.
Reported-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Yuchung Cheng <ycheng@google.com>
Tested-by: Rick Jones <rick.jones2@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
If we don't have a cluster, don't bother trying to allocate from it,
jumping right away to the attempt to allocate a new cluster.
Signed-off-by: Alexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
We test whether a block group has enough free space to hold the
requested block, but when we're doing clustered allocation, we can
save some cycles by testing whether it has enough room for the cluster
upfront, otherwise we end up attempting to set up a cluster and
failing. Only in the NO_EMPTY_SIZE loop do we attempt an unclustered
allocation, and by then we'll have zeroed the cluster size, so this
patch won't stop us from using the block group as a last resort.
Signed-off-by: Alexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Instead of starting at zero (offset is always zero), request a cluster
starting at search_start, that denotes the beginning of the current
block group.
Signed-off-by: Alexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
The field that indicates the size of the largest contiguous chunk of
free space in the cluster is not initialized when setting up bitmaps,
it's only increased when we find a larger contiguous chunk. We end up
retaining a larger value than appropriate for highly-fragmented
clusters, which may cause pointless searches for large contiguous
groups, and even cause clusters that do not meet the density
requirements to be set up.
Signed-off-by: Alexandre Oliva <oliva@lsd.ic.unicamp.br>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
We're failing to create clusters with bitmaps because
setup_cluster_no_bitmap checks that the list is empty before inserting
the bitmap entry in the list for setup_cluster_bitmap, but the list
field is only initialized when it is restored from the on-disk free
space cache, or when it is written out to disk.
Besides a potential race condition due to the multiple use of the list
field, filesystem performance severely degrades over time: as we use
up all non-bitmap free extents, the try-to-set-up-cluster dance is
done at every metadata block allocation. For every block group, we
fail to set up a cluster, and after failing on them all up to twice,
we fall back to the much slower unclustered allocation.
To make matters worse, before the unclustered allocation, we try to
create new block groups until we reach the 1% threshold, which
introduces additional bitmaps and thus block groups that we'll iterate
over at each metadata block request.
To reproduce this bug:
# dd if=/dev/zero of=img bs=1M count=256
# mkfs.btrfs img
# losetup -r /dev/loop1 img
# mount /dev/loop1 /mnt
OOPS!!
It triggered BUG_ON(!nr_devices) in btrfs_calc_avail_data_space().
To fix this, instead of checking write-only devices, we check all open
deivces:
# df -h /dev/loop1
Filesystem Size Used Avail Use% Mounted on
/dev/loop1 250M 28K 238M 1% /mnt
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
It seems overly harsh to fail a resize of a btrfs file system to the
same size when a shrink or grow would succeed. User app GParted trips
over this error. Allow it by bypassing the shrink or grow operation.
Signed-off-by: Mike Fleetwood <mike.fleetwood@googlemail.com>
When I ran the xfstests, I found the test tasks was blocked on meta-data
reservation.
By debugging, I found the reason of this bug:
start transaction
|
v
reserve meta-data space
|
v
flush delay allocation -> iput inode -> evict inode
^ |
| v
wait for delay allocation flush <- reserve meta-data space
And besides that, the flush on evicting inode will block the thread, which
is reclaiming the memory, and make oom happen easily.
Fix this bug by skipping the flush step when evicting inode.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
The location of the btrfs-progs repository has been changed.
This patch updates the documentation accordingly.
Signed-off-by: Arnd Hannemann <arnd@arndnet.de>
This adds support for byte queue limits and aggregates statistics
update (suggestion from Eric).
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@drr.davemloft.net>
in iSCSI SD mode to bnx2x device assigned single mac address
which is supposted to be iscsi mac. If this mode is recognized
bnx2x will disable LRO, decrease number of queues to 1 and rx ring
size to the minumum allowed by FW, this in order minimize memory use.
It will tranfer mac for iscsi usage and zero primary mac of the netdev.
Signed-off-by: Dmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
"cfg->drvid" comes from the user so there is a possibility they
didn't NUL terminate it properly.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
These strings come from the user. We strcpy() them inside
cf_command() so we should check that they are NULL terminated and
return an error if not.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch adds support for legacy Bosch CC770 and Intel AN82527 CAN
controllers on the ISA or PC-104 bus. The I/O port or memory address
and the IRQ number must be specified via module parameters:
insmod cc770_isa.ko port=0x310,0x380 irq=7,11
for ISA devices using I/O ports or:
insmod cc770_isa.ko mem=0xd1000,0xd1000 irq=7,11
for memory mapped ISA devices.
Indirect access via address and data port is supported as well:
insmod cc770_isa.ko port=0x310,0x380 indirect=1 irq=7,11
Furthermore, the following mode parameter can be defined:
clk: External oscillator clock frequency (default=16000000 [16 MHz])
cir: CPU interface register (default=0x40 [CPU_DSC])
ocr, Bus configuration register (default=0x00)
cor, Clockout register (default=0x00)
Note: for clk, cir, bcr and cor, the first argument re-defines the
default for all other devices, e.g.:
insmod cc770_isa.ko mem=0xd1000,0xd1000 irq=7,11 clk=24000000
is equivalent to
insmod cc770_isa.ko mem=0xd1000,0xd1000 irq=7,11 clk=24000000,24000000
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add some basic regulator support for the power pins, as needed
by the ST-Ericsson Snowball platform that powers up the SMSC911
chip using an external regulator.
Platforms that use regulators and the smsc911x and have no defined
regulator for the smsc911x and claim complete regulator
constraints with no dummy regulators will need to provide it, for
example using a fixed voltage regulator. It appears that this may
affect (apart from Ux500 Snowball) possibly these archs/machines
that from some grep:s appear to define both CONFIG_SMSC911X and
CONFIG_REGULATOR:
- ARM Freescale mx3 and OMAP 2 plus, Raumfeld machines
- Blackfin
- Super-H
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: linux-sh@vger.kernel.org
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-omap@vger.kernel.org
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: uclinux-dist-devel@blackfin.uclinux.org
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Robert Marklund <robert.marklund@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This driver is currently not supported on x86_64 systems because the
"isa_driver" interface is used (CONFIG_ISA=y). To overcome this
limitation, the driver is converted to a platform driver, similar to
the serial 8250 driver.
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit 7dc00c82 added a 'notify' parameter for vif_delete() to
distinguish whether to unregister the device.
When notify=1 means we does not need to unregister the device,
so calling unregister_netdevice_many is useless.
Signed-off-by: RongQing.Li <roy.qing.li@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch fixes the compiler warnings: "comparison is always
false due to limited range of data type" by using "0xff" instead
of "-1" for unsigned values.
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Change function rcu_dereference to rcu_dereference_bh to avoid warning
[ INFO: suspicious RCU usage. ]
-------------------------------
net/core/dev.c:2459 suspicious rcu_dereference_check() usage!
because we are locking with
rcu_read_lock_bh();
in function dev_queue_xmit(struct sk_buff *skb)
Signed-off-by: Igor Maravic <igorm@etf.rs>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: Update comments describing device power management callbacks
PM / Sleep: Update documentation related to system wakeup
PM / Runtime: Make documentation follow the new behavior of irq_safe
PM / Sleep: Correct inaccurate information in devices.txt
PM / Domains: Document how PM domains are used by the PM core
PM / Hibernate: Do not leak memory in error/test code paths
A recent fix to the the NetLabel code caused build problem with
configurations that did not have IPv6 enabled; see below:
netlabel_kapi.c: In function 'netlbl_cfg_unlbl_map_add':
netlabel_kapi.c:165:4:
error: implicit declaration of function 'netlbl_af6list_add'
This patch fixes this problem by making the IPv6 specific code conditional
on the IPv6 configuration flags as we done in the rest of NetLabel and the
network stack as a whole. We have to move some variable declarations
around as a result so things may not be quite as pretty, but at least it
builds cleanly now.
Some additional IPv6 conditionals were added to the NetLabel code as well
for the sake of consistency.
Reported-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Paul Moore <pmoore@redhat.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Commit f2c31e32b3 ("net: fix NULL dereferences in check_peer_redir()")
forgot to take care of infiniband uses of dst neighbours.
Many thanks to Marc Aurele who provided a nice bug report and feedback.
Reported-by: Marc Aurele La France <tsi@ualberta.ca>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: <stable@kernel.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
This following can occur with ipoib when processing a multicast reponse:
BUG: soft lockup - CPU#0 stuck for 67s! [ib_mad1:982]
Modules linked in: ...
CPU 0:
Modules linked in: ...
Pid: 982, comm: ib_mad1 Not tainted 2.6.32-131.0.15.el6.x86_64 #1 ProLiant DL160 G5
RIP: 0010:[<ffffffff814ddb27>] [<ffffffff814ddb27>] _spin_unlock_irqrestore+0x17/0x20
RSP: 0018:ffff8802119ed860 EFLAGS: 00000246
0000000000000004 RBX: ffff8802119ed860 RCX: 000000000000a299
RDX: ffff88021086c700 RSI: 0000000000000246 RDI: 0000000000000246
RBP: ffffffff8100bc8e R08: ffff880210ac229c R09: 0000000000000000
R10: ffff88021278aab8 R11: 0000000000000000 R12: ffff8802119ed860
R13: ffffffff8100be6e R14: 0000000000000001 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff880028200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b
CR2: 00000000006d4840 CR3: 0000000209aa5000 CR4: 00000000000406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
[<ffffffffa032c247>] ? ipoib_mcast_send+0x157/0x480 [ib_ipoib]
[<ffffffff8100bc8e>] ? apic_timer_interrupt+0xe/0x20
[<ffffffff8100bc8e>] ? apic_timer_interrupt+0xe/0x20
[<ffffffffa03283d4>] ? ipoib_path_lookup+0x124/0x2d0 [ib_ipoib]
[<ffffffffa03286fc>] ? ipoib_start_xmit+0x17c/0x430 [ib_ipoib]
[<ffffffff8141e758>] ? dev_hard_start_xmit+0x2c8/0x3f0
[<ffffffff81439d0a>] ? sch_direct_xmit+0x15a/0x1c0
[<ffffffff81423098>] ? dev_queue_xmit+0x388/0x4d0
[<ffffffffa032d6b7>] ? ipoib_mcast_join_finish+0x2c7/0x510 [ib_ipoib]
[<ffffffffa032dab8>] ? ipoib_mcast_sendonly_join_complete+0x1b8/0x1f0 [ib_ipoib]
[<ffffffffa02a0946>] ? mcast_work_handler+0x1a6/0x710 [ib_sa]
[<ffffffffa015f01e>] ? ib_send_mad+0xfe/0x3c0 [ib_mad]
[<ffffffffa00f6c93>] ? ib_get_cached_lmc+0xa3/0xb0 [ib_core]
[<ffffffffa02a0f9b>] ? join_handler+0xeb/0x200 [ib_sa]
[<ffffffffa029e4fc>] ? ib_sa_mcmember_rec_callback+0x5c/0xa0 [ib_sa]
[<ffffffffa029e79c>] ? recv_handler+0x3c/0x70 [ib_sa]
[<ffffffffa01603a4>] ? ib_mad_completion_handler+0x844/0x9d0 [ib_mad]
[<ffffffffa015fb60>] ? ib_mad_completion_handler+0x0/0x9d0 [ib_mad]
[<ffffffff81088830>] ? worker_thread+0x170/0x2a0
[<ffffffff8108e160>] ? autoremove_wake_function+0x0/0x40
[<ffffffff810886c0>] ? worker_thread+0x0/0x2a0
[<ffffffff8108ddf6>] ? kthread+0x96/0xa0
[<ffffffff8100c1ca>] ? child_rip+0xa/0x20
Coinciding with stack trace is the following message:
ib0: ib_address_create failed
The code below in ipoib_mcast_join_finish() will note the above
failure in the address handle but otherwise continue:
ah = ipoib_create_ah(dev, priv->pd, &av);
if (!ah) {
ipoib_warn(priv, "ib_address_create failed\n");
} else {
The while loop at the bottom of ipoib_mcast_join_finish() will attempt
to send queued multicast packets in mcast->pkt_queue and eventually
end up in ipoib_mcast_send():
if (!mcast->ah) {
if (skb_queue_len(&mcast->pkt_queue) < IPOIB_MAX_MCAST_QUEUE)
skb_queue_tail(&mcast->pkt_queue, skb);
else {
++dev->stats.tx_dropped;
dev_kfree_skb_any(skb);
}
My read is that the code will requeue the packet and return to the
ipoib_mcast_join_finish() while loop and the stage is set for the
"hung" task diagnostic as the while loop never sees a non-NULL ah, and
will do nothing to resolve.
There are GFP_ATOMIC allocates in the provider routines, so this is
possible and should be dealt with.
The test that induced the failure is associated with a host SM on the
same server during a shutdown.
This patch causes ipoib_mcast_join_finish() to exit with an error
which will flush the queued mcast packets. Nothing is done to unwind
the QP attached state so that subsequent sends from above will retry
the join.
Reviewed-by: Ram Vepa <ram.vepa@qlogic.com>
Reviewed-by: Gary Leshner <gary.leshner@qlogic.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
The check from commit 30c2235c is incomplete and cannot prevent
cases like key_len = 0x80000000 (INT_MAX + 1). In that case, the
left-hand side of the check (INT_MAX - key_len), which is unsigned,
becomes 0xffffffff (UINT_MAX) and bypasses the check.
However this shouldn't be a security issue. The function is called
from the following two code paths:
1) setsockopt()
2) sctp_auth_asoc_set_secret()
In case (1), sca_keylength is never going to exceed 65535 since it's
bounded by a u16 from the user API. As such, the key length will
never overflow.
In case (2), sca_keylength is computed based on the user key (1 short)
and 2 * key_vector (3 shorts) for a total of 7 * USHRT_MAX, which still
will not overflow.
In other words, this overflow check is not really necessary. Just
make it more correct.
Signed-off-by: Xi Wang <xi.wang@gmail.com>
Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
* 'slab/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
slub: avoid potential NULL dereference or corruption
slub: use irqsafe_cpu_cmpxchg for put_cpu_partial
slub: move discard_slab out of node lock
slub: use correct parameter to add a page to partial list tail
Instead of using a custom flow dissector, use skb_flow_dissect() and
benefit from tunnelling support.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Instead of using a custom flow dissector, use skb_flow_dissect() and
benefit from tunnelling support.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp_sendmsg() uses select_size() helper to choose skb head size when a
new skb must be allocated.
If GSO is enabled for the socket, current strategy is to force all
payload data to be outside of headroom, in PAGE fragments.
This strategy is not welcome for small packets, wasting memory.
Experiments show that best results are obtained when using 2048 bytes
for skb head (This includes the skb overhead and various headers)
This patch provides better len/truesize ratios for packets sent to
loopback device, and reduce memory needs for in-flight loopback packets,
particularly on arches with big pages.
If a sender sends many 1-byte packets to an unresponsive application,
receiver rmem_alloc will grow faster and will stop queuing these packets
sooner, or will collapse its receive queue to free excess memory.
netperf -t TCP_RR results are improved by ~4 %, and many workloads are
improved as well (tbench, mysql...)
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Le lundi 28 novembre 2011 à 19:06 -0500, David Miller a écrit :
> From: Dimitris Michailidis <dm@chelsio.com>
> Date: Mon, 28 Nov 2011 08:25:39 -0800
>
> >> +bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys
> >> *flow)
> >> +{
> >> + int poff, nhoff = skb_network_offset(skb);
> >> + u8 ip_proto;
> >> + u16 proto = skb->protocol;
> >
> > __be16 instead of u16 for proto?
>
> I'll take care of this when I apply these patches.
( CC trimmed )
Thanks David !
Here is a small patch to use one 64bit load/store on x86_64 instead of
two 32bit load/stores.
[PATCH net-next] flow_dissector: use a 64bit load/store
gcc compiler is smart enough to use a single load/store if we
memcpy(dptr, sptr, 8) on x86_64, regardless of
CONFIG_CC_OPTIMIZE_FOR_SIZE
In IP header, daddr immediately follows saddr, this wont change in the
future. We only need to make sure our flow_keys (src,dst) fields wont
break the rule.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changes to sfc to use byte queue limits.
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changes to bnx2x to use byte queue limits.
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changes to tg3 to use byte queue limits.
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changes to forcedeth to use byte queue limits.
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Changes to e1000e to use byte queue limits.
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Networking stack support for byte queue limits, uses dynamic queue
limits library. Byte queue limits are maintained per transmit queue,
and a dql structure has been added to netdev_queue structure for this
purpose.
Configuration of bql is in the tx-<n> sysfs directory for the queue
under the byte_queue_limits directory. Configuration includes:
limit_min, bql minimum limit
limit_max, bql maximum limit
hold_time, bql slack hold time
Also under the directory are:
limit, current byte limit
inflight, current number of bytes on the queue
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This patch moves the xps specific parts in netdev_queue_release into
its own function which netdev_queue_release can call. This allows
netdev_queue_release to be more generic (for adding new attributes
to tx queues).
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add interfaces for drivers to call for recording number of packets and
bytes at send time and transmit completion. Also, added a function to
"reset" a queue. These will be used by Byte Queue Limits.
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Create separate queue state flags so that either the stack or drivers
can turn on XOFF. Added a set of functions used in the stack to determine
if a queue is really stopped (either by stack or driver)
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Implementation of dynamic queue limits (dql). This is a libary which
allows a queue limit to be dynamically managed. The goal of dql is
to set the queue limit, number of objects to the queue, to be minimized
without allowing the queue to be starved.
dql would be used with a queue which has these properties:
1) Objects are queued up to some limit which can be expressed as a
count of objects.
2) Periodically a completion process executes which retires consumed
objects.
3) Starvation occurs when limit has been reached, all queued data has
actually been consumed but completion processing has not yet run,
so queuing new data is blocked.
4) Minimizing the amount of queued data is desirable.
A canonical example of such a queue would be a NIC HW transmit queue.
The queue limit is dynamic, it will increase or decrease over time
depending on the workload. The queue limit is recalculated each time
completion processing is done. Increases occur when the queue is
starved and can exponentially increase over successive intervals.
Decreases occur when more data is being maintained in the queue than
needed to prevent starvation. The number of extra objects, or "slack",
is measured over successive intervals, and to avoid hysteresis the
limit is only reduced by the miminum slack seen over a configurable
time period.
dql API provides routines to manage the queue:
- dql_init is called to intialize the dql structure
- dql_reset is called to reset dynamic values
- dql_queued called when objects are being enqueued
- dql_avail returns availability in the queue
- dql_completed is called when objects have be consumed in the queue
Configuration consists of:
- max_limit, maximum limit
- min_limit, minimum limit
- slack_hold_time, time to measure instances of slack before reducing
queue limit
Signed-off-by: Tom Herbert <therbert@google.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Eric Dumazet