Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422915AbWLUJQH (ORCPT ); Thu, 21 Dec 2006 04:16:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422914AbWLUJPO (ORCPT ); Thu, 21 Dec 2006 04:15:14 -0500 Received: from dea.vocord.ru ([217.67.177.50]:47304 "EHLO kano.factory.vocord.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1422901AbWLUJPE convert rfc822-to-8bit (ORCPT ); Thu, 21 Dec 2006 04:15:04 -0500 Cc: David Miller , Ulrich Drepper , Andrew Morton , Evgeniy Polyakov , netdev , Zach Brown , Christoph Hellwig , Chase Venters , Johann Borck , linux-kernel@vger.kernel.org, Jeff Garzik Subject: [take28-resend_1->0 0/8] kevent: Generic event handling mechanism. In-Reply-To: <3154985aa0591036@2ka.mipt.ru> X-Mailer: gregkh_patchbomb Date: Thu, 21 Dec 2006 12:14:17 +0300 Message-Id: <11666924573643@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Reply-To: Evgeniy Polyakov To: Evgeniy Polyakov Content-Transfer-Encoding: 7BIT From: Evgeniy Polyakov Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 11476 Lines: 259 Generic event handling mechanism. Kevent is a generic subsytem which allows to handle event notifications. It supports both level and edge triggered events. It is similar to poll/epoll in some cases, but it is more scalable, it is faster and allows to work with essentially eny kind of events. Events are provided into kernel through control syscall and can be read back through ring buffer or using usual syscalls. Kevent update (i.e. readiness switching) happens directly from internals of the appropriate state machine of the underlying subsytem (like network, filesystem, timer or any other). Homepage: http://tservice.net.ru/~s0mbre/old/?section=projects&item=kevent Documentation page: http://linux-net.osdl.org/index.php/Kevent Consider for inclusion. New benchmark, which can be a hoax though, can be found at http://tservice.net.ru/~s0mbre/blog/2006/11/30#2006_11_30 where kevent on amd64 with 1gb of ram can handle more than 7200 events per second with 8000 requests concurrency with 'ab' benchmark and lighttpd. Although I tought it should not be published due to possible errors, I decided to send it for review. With this release I start 3 days resending timeout - i.e. each third day I will send either new version (if something new was requested and agreed to be implemented) or resending with back counter started from three. When back counter hits zero after three resending I consider there is no interest in subsystem and I will stop further sending. Thanks for understanding and your time. Changes from 'take27' patchset: * made kevent default yes in non embedded case. * added falgs to callback structures - currently used to check if kevent can be requested from kernelspace only (posix timers) or userspace (all others) Changes from 'take26' patchset: * made kevent visible in config only in case of embedded setup. * added comment about KEVENT_MAX number. * spell fix. Changes from 'take25' patchset: * use timespec as timeout parameter. * added high-resolution timer to handle absolute timeouts. * added flags to waiting and initialization syscalls. * kevent_commit() has new_uidx parameter. * kevent_wait() has old_uidx parameter, which, if not equal to u->uidx, results in immediate wakeup (usefull for the case when entries are added asynchronously from kernel (not supported for now)). * added interface to mark any event as ready. * event POSIX timers support. * return -ENOSYS if there is no registered event type. * provided file descriptor must be checked for fifo type (spotted by Eric Dumazet). * signal notifications. * documentation update. * lighttpd patch updated (the latest benchmarks with lighttpd patch can be found in blog). Changes from 'take24' patchset: * new (old (new)) ring buffer implementation with kernel and user indexes. * added initialization syscall instead of opening /dev/kevent * kevent_commit() syscall to commit ring buffer entries * changed KEVENT_REQ_WAKEUP_ONE flag to KEVENT_REQ_WAKEUP_ALL, kevent wakes only first thread always if that flag is not set * KEVENT_REQ_ALWAYS_QUEUE flag. If set, kevent will be queued into ready queue instead of copying back to userspace when kevent is ready immediately when it is added. * lighttpd patch (Hail! Although nothing really outstanding compared to epoll) Changes from 'take23' patchset: * kevent PIPE notifications * KEVENT_REQ_LAST_CHECK flag, which allows to perform last check at dequeueing time * fixed poll/select notifications (were broken due to tree manipulations) * made Documentation/kevent.txt look nice in 80-col terminal * fix for copy_to_user() failure report for the first kevent (Andrew Morton) * minor function renames Changes from 'take22' patchset: * new ring buffer implementation in process' memory * wakeup-one-thread flag * edge-triggered behaviour Changes from 'take21' patchset: * minor cleanups (different return values, removed unneded variables, whitespaces and so on) * fixed bug in kevent removal in case when kevent being removed is the same as overflow_kevent (spotted by Eric Dumazet) Changes from 'take20' patchset: * new ring buffer implementation * removed artificial limit on possible number of kevents Changes from 'take19' patchset: * use __init instead of __devinit * removed 'default N' from config for user statistic * removed kevent_user_fini() since kevent can not be unloaded * use KERN_INFO for statistic output Changes from 'take18' patchset: * use __init instead of __devinit * removed 'default N' from config for user statistic * removed kevent_user_fini() since kevent can not be unloaded * use KERN_INFO for statistic output Changes from 'take17' patchset: * Use RB tree instead of hash table. At least for a web sever, frequency of addition/deletion of new kevent is comparable with number of search access, i.e. most of the time events are added, accesed only couple of times and then removed, so it justifies RB tree usage over AVL tree, since the latter does have much slower deletion time (max O(log(N)) compared to 3 ops), although faster search time (1.44*O(log(N)) vs. 2*O(log(N))). So for kevents I use RB tree for now and later, when my AVL tree implementation is ready, it will be possible to compare them. * Changed readiness check for socket notifications. With both above changes it is possible to achieve more than 3380 req/second compared to 2200, sometimes 2500 req/second for epoll() for trivial web-server and httperf client on the same hardware. It is possible that above kevent limit is due to maximum allowed kevents in a time limit, which is 4096 events. Changes from 'take16' patchset: * misc cleanups (__read_mostly, const ...) * created special macro which is used for mmap size (number of pages) calculation * export kevent_socket_notify(), since it is used in network protocols which can be built as modules (IPv6 for example) Changes from 'take15' patchset: * converted kevent_timer to high-resolution timers, this forces timer API update at http://linux-net.osdl.org/index.php/Kevent * use struct ukevent* instead of void * in syscalls (documentation has been updated) * added warning in kevent_add_ukevent() if ring has broken index (for testing) Changes from 'take14' patchset: * added kevent_wait() This syscall waits until either timeout expires or at least one event becomes ready. It also commits that @num events from @start are processed by userspace and thus can be be removed or rearmed (depending on it's flags). It can be used for commit events read by userspace through mmap interface. Example userspace code (evtest.c) can be found on project's homepage. * added socket notifications (send/recv/accept) Changes from 'take13' patchset: * do not get lock aroung user data check in __kevent_search() * fail early if there were no registered callbacks for given type of kevent * trailing whitespace cleanup Changes from 'take12' patchset: * remove non-chardev interface for initialization * use pointer to kevent_mring instead of unsigned longs * use aligned 64bit type in raw user data (can be used by high-res timer if needed) * simplified enqueue/dequeue callbacks and kevent initialization * use nanoseconds for timeout * put number of milliseconds into timer's return data * move some definitions into user-visible header * removed filenames from comments Changes from 'take11' patchset: * include missing headers into patchset * some trivial code cleanups (use goto instead of if/else games and so on) * some whitespace cleanups * check for ready_callback() callback before main loop which should save us some ticks Changes from 'take10' patchset: * removed non-existent prototypes * added helper function for kevent_registered_callbacks * fixed 80 lines comments issues * added shared between userspace and kernelspace header instead of embedd them in one * core restructuring to remove forward declarations * s o m e w h i t e s p a c e c o d y n g s t y l e c l e a n u p * use vm_insert_page() instead of remap_pfn_range() Changes from 'take9' patchset: * fixed ->nopage method Changes from 'take8' patchset: * fixed mmap release bug * use module_init() instead of late_initcall() * use better structures for timer notifications Changes from 'take7' patchset: * new mmap interface (not tested, waiting for other changes to be acked) - use nopage() method to dynamically substitue pages - allocate new page for events only when new added kevent requres it - do not use ugly index dereferencing, use structure instead - reduced amount of data in the ring (id and flags), maximum 12 pages on x86 per kevent fd Changes from 'take6' patchset: * a lot of comments! * do not use list poisoning for detection of the fact, that entry is in the list * return number of ready kevents even if copy*user() fails * strict check for number of kevents in syscall * use ARRAY_SIZE for array size calculation * changed superblock magic number * use SLAB_PANIC instead of direct panic() call * changed -E* return values * a lot of small cleanups and indent fixes Changes from 'take5' patchset: * removed compilation warnings about unused wariables when lockdep is not turned on * do not use internal socket structures, use appropriate (exported) wrappers instead * removed default 1 second timeout * removed AIO stuff from patchset Changes from 'take4' patchset: * use miscdevice instead of chardevice * comments fixes Changes from 'take3' patchset: * removed serializing mutex from kevent_user_wait() * moved storage list processing to RCU * removed lockdep screaming - all storage locks are initialized in the same function, so it was learned to differentiate between various cases * remove kevent from storage if is marked as broken after callback * fixed a typo in mmaped buffer implementation which would end up in wrong index calcualtion Changes from 'take2' patchset: * split kevent_finish_user() to locked and unlocked variants * do not use KEVENT_STAT ifdefs, use inline functions instead * use array of callbacks of each type instead of each kevent callback initialization * changed name of ukevent guarding lock * use only one kevent lock in kevent_user for all hash buckets instead of per-bucket locks * do not use kevent_user_ctl structure instead provide needed arguments as syscall parameters * various indent cleanups * added optimisation, which is aimed to help when a lot of kevents are being copied from userspace * mapped buffer (initial) implementation (no userspace yet) Changes from 'take1' patchset: - rebased against 2.6.18-git tree - removed ioctl controlling - added new syscall kevent_get_events(int fd, unsigned int min_nr, unsigned int max_nr, unsigned int timeout, void __user *buf, unsigned flags) - use old syscall kevent_ctl for creation/removing, modification and initial kevent initialization - use mutuxes instead of semaphores - added file descriptor check and return error if provided descriptor does not match kevent file operations - various indent fixes - removed aio_sendfile() declarations. Thank you. Signed-off-by: Evgeniy Polyakov - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/