From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- Documentation/networking/eql.rst | 373 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 373 insertions(+) create mode 100644 Documentation/networking/eql.rst (limited to 'Documentation/networking/eql.rst') diff --git a/Documentation/networking/eql.rst b/Documentation/networking/eql.rst new file mode 100644 index 000000000..a628c4c81 --- /dev/null +++ b/Documentation/networking/eql.rst @@ -0,0 +1,373 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================================== +EQL Driver: Serial IP Load Balancing HOWTO +========================================== + + Simon "Guru Aleph-Null" Janes, simon@ncm.com + + v1.1, February 27, 1995 + + This is the manual for the EQL device driver. EQL is a software device + that lets you load-balance IP serial links (SLIP or uncompressed PPP) + to increase your bandwidth. It will not reduce your latency (i.e. ping + times) except in the case where you already have lots of traffic on + your link, in which it will help them out. This driver has been tested + with the 1.1.75 kernel, and is known to have patched cleanly with + 1.1.86. Some testing with 1.1.92 has been done with the v1.1 patch + which was only created to patch cleanly in the very latest kernel + source trees. (Yes, it worked fine.) + +1. Introduction +=============== + + Which is worse? A huge fee for a 56K leased line or two phone lines? + It's probably the former. If you find yourself craving more bandwidth, + and have a ISP that is flexible, it is now possible to bind modems + together to work as one point-to-point link to increase your + bandwidth. All without having to have a special black box on either + side. + + + The eql driver has only been tested with the Livingston PortMaster-2e + terminal server. I do not know if other terminal servers support load- + balancing, but I do know that the PortMaster does it, and does it + almost as well as the eql driver seems to do it (-- Unfortunately, in + my testing so far, the Livingston PortMaster 2e's load-balancing is a + good 1 to 2 KB/s slower than the test machine working with a 28.8 Kbps + and 14.4 Kbps connection. However, I am not sure that it really is + the PortMaster, or if it's Linux's TCP drivers. I'm told that Linux's + TCP implementation is pretty fast though.--) + + + I suggest to ISPs out there that it would probably be fair to charge + a load-balancing client 75% of the cost of the second line and 50% of + the cost of the third line etc... + + + Hey, we can all dream you know... + + +2. Kernel Configuration +======================= + + Here I describe the general steps of getting a kernel up and working + with the eql driver. From patching, building, to installing. + + +2.1. Patching The Kernel +------------------------ + + If you do not have or cannot get a copy of the kernel with the eql + driver folded into it, get your copy of the driver from + ftp://slaughter.ncm.com/pub/Linux/LOAD_BALANCING/eql-1.1.tar.gz. + Unpack this archive someplace obvious like /usr/local/src/. It will + create the following files:: + + -rw-r--r-- guru/ncm 198 Jan 19 18:53 1995 eql-1.1/NO-WARRANTY + -rw-r--r-- guru/ncm 30620 Feb 27 21:40 1995 eql-1.1/eql-1.1.patch + -rwxr-xr-x guru/ncm 16111 Jan 12 22:29 1995 eql-1.1/eql_enslave + -rw-r--r-- guru/ncm 2195 Jan 10 21:48 1995 eql-1.1/eql_enslave.c + + Unpack a recent kernel (something after 1.1.92) someplace convenient + like say /usr/src/linux-1.1.92.eql. Use symbolic links to point + /usr/src/linux to this development directory. + + + Apply the patch by running the commands:: + + cd /usr/src + patch + ". Here are some example enslavings:: + + eql_enslave eql sl0 28800 + eql_enslave eql ppp0 14400 + eql_enslave eql sl1 57600 + + When you want to free a device from its life of slavery, you can + either down the device with ifconfig (eql will automatically bury the + dead slave and remove it from its queue) or use eql_emancipate to free + it. (-- Or just ifconfig it down, and the eql driver will take it out + for you.--):: + + eql_emancipate eql sl0 + eql_emancipate eql ppp0 + eql_emancipate eql sl1 + + +3.3. DSLIP Configuration for the eql Device +------------------------------------------- + + The general idea is to bring up and keep up as many SLIP connections + as you need, automatically. + + +3.3.1. /etc/slip/runslip.conf +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + + Here is an example runslip.conf:: + + name sl-line-1 + enabled + baud 38400 + mtu 576 + ducmd -e /etc/slip/dialout/cua2-288.xp -t 9 + command eql_enslave eql $interface 28800 + address 198.67.33.239 + line /dev/cua2 + + name sl-line-2 + enabled + baud 38400 + mtu 576 + ducmd -e /etc/slip/dialout/cua3-288.xp -t 9 + command eql_enslave eql $interface 28800 + address 198.67.33.239 + line /dev/cua3 + + +3.4. Using PPP and the eql Device +--------------------------------- + + I have not yet done any load-balancing testing for PPP devices, mainly + because I don't have a PPP-connection manager like SLIP has with + DSLIP. I did find a good tip from LinuxNET:Billy for PPP performance: + make sure you have asyncmap set to something so that control + characters are not escaped. + + + I tried to fix up a PPP script/system for redialing lost PPP + connections for use with the eql driver the weekend of Feb 25-26 '95 + (Hereafter known as the 8-hour PPP Hate Festival). Perhaps later this + year. + + +4. About the Slave Scheduler Algorithm +====================================== + + The slave scheduler probably could be replaced with a dozen other + things and push traffic much faster. The formula in the current set + up of the driver was tuned to handle slaves with wildly different + bits-per-second "priorities". + + + All testing I have done was with two 28.8 V.FC modems, one connecting + at 28800 bps or slower, and the other connecting at 14400 bps all the + time. + + + One version of the scheduler was able to push 5.3 K/s through the + 28800 and 14400 connections, but when the priorities on the links were + very wide apart (57600 vs. 14400) the "faster" modem received all + traffic and the "slower" modem starved. + + +5. Testers' Reports +=================== + + Some people have experimented with the eql device with newer + kernels (than 1.1.75). I have since updated the driver to patch + cleanly in newer kernels because of the removal of the old "slave- + balancing" driver config option. + + + - icee from LinuxNET patched 1.1.86 without any rejects and was able + to boot the kernel and enslave a couple of ISDN PPP links. + +5.1. Randolph Bentson's Test Report +----------------------------------- + + :: + + From bentson@grieg.seaslug.org Wed Feb 8 19:08:09 1995 + Date: Tue, 7 Feb 95 22:57 PST + From: Randolph Bentson + To: guru@ncm.com + Subject: EQL driver tests + + + I have been checking out your eql driver. (Nice work, that!) + Although you may already done this performance testing, here + are some data I've discovered. + + Randolph Bentson + bentson@grieg.seaslug.org + +------------------------------------------------------------------ + + + A pseudo-device driver, EQL, written by Simon Janes, can be used + to bundle multiple SLIP connections into what appears to be a + single connection. This allows one to improve dial-up network + connectivity gradually, without having to buy expensive DSU/CSU + hardware and services. + + I have done some testing of this software, with two goals in + mind: first, to ensure it actually works as described and + second, as a method of exercising my device driver. + + The following performance measurements were derived from a set + of SLIP connections run between two Linux systems (1.1.84) using + a 486DX2/66 with a Cyclom-8Ys and a 486SLC/40 with a Cyclom-16Y. + (Ports 0,1,2,3 were used. A later configuration will distribute + port selection across the different Cirrus chips on the boards.) + Once a link was established, I timed a binary ftp transfer of + 289284 bytes of data. If there were no overhead (packet headers, + inter-character and inter-packet delays, etc.) the transfers + would take the following times:: + + bits/sec seconds + 345600 8.3 + 234600 12.3 + 172800 16.7 + 153600 18.8 + 76800 37.6 + 57600 50.2 + 38400 75.3 + 28800 100.4 + 19200 150.6 + 9600 301.3 + + A single line running at the lower speeds and with large packets + comes to within 2% of this. Performance is limited for the higher + speeds (as predicted by the Cirrus databook) to an aggregate of + about 160 kbits/sec. The next round of testing will distribute + the load across two or more Cirrus chips. + + The good news is that one gets nearly the full advantage of the + second, third, and fourth line's bandwidth. (The bad news is + that the connection establishment seemed fragile for the higher + speeds. Once established, the connection seemed robust enough.) + + ====== ======== === ======== ======= ======= === + #lines speed mtu seconds theory actual %of + kbit/sec duration speed speed max + ====== ======== === ======== ======= ======= === + 3 115200 900 _ 345600 + 3 115200 400 18.1 345600 159825 46 + 2 115200 900 _ 230400 + 2 115200 600 18.1 230400 159825 69 + 2 115200 400 19.3 230400 149888 65 + 4 57600 900 _ 234600 + 4 57600 600 _ 234600 + 4 57600 400 _ 234600 + 3 57600 600 20.9 172800 138413 80 + 3 57600 900 21.2 172800 136455 78 + 3 115200 600 21.7 345600 133311 38 + 3 57600 400 22.5 172800 128571 74 + 4 38400 900 25.2 153600 114795 74 + 4 38400 600 26.4 153600 109577 71 + 4 38400 400 27.3 153600 105965 68 + 2 57600 900 29.1 115200 99410.3 86 + 1 115200 900 30.7 115200 94229.3 81 + 2 57600 600 30.2 115200 95789.4 83 + 3 38400 900 30.3 115200 95473.3 82 + 3 38400 600 31.2 115200 92719.2 80 + 1 115200 600 31.3 115200 92423 80 + 2 57600 400 32.3 115200 89561.6 77 + 1 115200 400 32.8 115200 88196.3 76 + 3 38400 400 33.5 115200 86353.4 74 + 2 38400 900 43.7 76800 66197.7 86 + 2 38400 600 44 76800 65746.4 85 + 2 38400 400 47.2 76800 61289 79 + 4 19200 900 50.8 76800 56945.7 74 + 4 19200 400 53.2 76800 54376.7 70 + 4 19200 600 53.7 76800 53870.4 70 + 1 57600 900 54.6 57600 52982.4 91 + 1 57600 600 56.2 57600 51474 89 + 3 19200 900 60.5 57600 47815.5 83 + 1 57600 400 60.2 57600 48053.8 83 + 3 19200 600 62 57600 46658.7 81 + 3 19200 400 64.7 57600 44711.6 77 + 1 38400 900 79.4 38400 36433.8 94 + 1 38400 600 82.4 38400 35107.3 91 + 2 19200 900 84.4 38400 34275.4 89 + 1 38400 400 86.8 38400 33327.6 86 + 2 19200 600 87.6 38400 33023.3 85 + 2 19200 400 91.2 38400 31719.7 82 + 4 9600 900 94.7 38400 30547.4 79 + 4 9600 400 106 38400 27290.9 71 + 4 9600 600 110 38400 26298.5 68 + 3 9600 900 118 28800 24515.6 85 + 3 9600 600 120 28800 24107 83 + 3 9600 400 131 28800 22082.7 76 + 1 19200 900 155 19200 18663.5 97 + 1 19200 600 161 19200 17968 93 + 1 19200 400 170 19200 17016.7 88 + 2 9600 600 176 19200 16436.6 85 + 2 9600 900 180 19200 16071.3 83 + 2 9600 400 181 19200 15982.5 83 + 1 9600 900 305 9600 9484.72 98 + 1 9600 600 314 9600 9212.87 95 + 1 9600 400 332 9600 8713.37 90 + ====== ======== === ======== ======= ======= === + +5.2. Anthony Healy's Report +--------------------------- + + :: + + Date: Mon, 13 Feb 1995 16:17:29 +1100 (EST) + From: Antony Healey + To: Simon Janes + Subject: Re: Load Balancing + + Hi Simon, + I've installed your patch and it works great. I have trialed + it over twin SL/IP lines, just over null modems, but I was + able to data at over 48Kb/s [ISDN link -Simon]. I managed a + transfer of up to 7.5 Kbyte/s on one go, but averaged around + 6.4 Kbyte/s, which I think is pretty cool. :) -- cgit v1.3.1