On Mon, 2012-03-26 at 16:28 +0530, Mahesh Gondi wrote: > > > On Mon, Mar 26, 2012 at 3:38 PM, Davidlohr Bueso <[email protected]> wrote: > On Mon, 2012-03-26 at 02:56 -0300, Felipe Astroza Araya wrote: > > Good aproach. It's like a stack (LIFO) of sched_connections > BUT I'd prefer a linked list, because it's simpler. You could > use just a "free list" and not two arrays (stack and queue). > When a connection is closed his sched_connection is returned > to the "free list" (head). > > > > > It seems to be this is an overkill and the optimization is too > small. We > can always maintain a global variable with the size of current > capacity > - since in a threaded context it would require locking which > might lead > to contention. Another alternative is to keep a bitmap instead > of a new > free_in_queue array. So the bitmap would have a size of > work_capacity > each time a slot is occupied, the corresponding bit is set. > Bitmaps are > O(1) as well and the overhead is just 1 bit per setting > > In case of bitmaps O(1) will be if I am checking the value of a > particular position. But for finding a free bit it will be O(n/t) , > t=sizeof(datatype used beneath)==> O(n), with very very low constants.
No! The whole point of bitmaps is speed and simplicity: we don't iterate over the map sequentially and use instead bit operations. For example to set a bit at position N: unsigned long *p = ((unsigned long *)worker_capacity_addr) + worker_capacity/BITS_PER_LONG; *p &= ~((1 << ((worker_capcity) % BITS_PER_LONG))) where BITS_PER_LONG is 32 or 64 depending on the architecture. > Since, we're not working with a worker_capacity being very very large > these low-valued constants will come into play and prove very > helpyful. Correct, which is why I think that optimizations here aren't very useful - O(n) is just fine when dealing with small ranges. > > > > Another issue in mk_scheduler is mk_sched_get_connection(). > This function is called from mk_conn_write() and > mk_sched_remove_client(). The mk_sched_get_connection()'s > complexity is O(work_capacity), is used two times at least in > connection life when it could be avoid completely. epoll_wait > returns a event array and Monkey uses the socket fd as > epoll_event data. That's wrong decision!, epoll_event data > should be the sched_connection and NOT the socket fd. It's > possible to improve it, but need hard work. > > > > El 26-03-2012, a las 1:22, Eduardo Silva escribió: > > > > > Hi, > > > > > > thanks for the patch. Looking with valgrind seems to be > optimized a > > > little bit, screenshot here: > > > > > > > http://edsiper.linuxchile.cl/sched_optimization_001.png > > > > > > without optimization mk_sched_register() takes 0.40 for > 5000 calls, > > > the same situation but for an optimized code takes 0.36. > Its an > > > improvement. > > > > > > Dave, Zeus and Max, what do you think about the patch ? > > > > > > cheers, > > > > > > > > > On Sun, Mar 25, 2012 at 9:43 PM, Mahesh Gondi > <[email protected]> wrote: > > >> Hi all, > > >> > > >> I made some changes to mk_scheduler.c. First I will > explain in brief what I > > >> did before the results. > > >> > > >> In mk_scheduler.c , the mk_sched_register_client serves > the purpose of > > >> adding new client requests to the worker thread > queue(everything discussed > > >> here happens in the thread context). Adding was done by > iterating over the > > >> queue to looking for an available spot to be inserted. > When the load on > > >> server is at near max, then this insertion cost rises to > O(work_capacity). > > >> > > >> Instead I maintained free spots on the queue(list of > client requests > > >> received), in a simple array of size (work_capacity+1) > with each element > > >> pointing to an index in queue(first element kept a count > of number of free > > >> spots available). Array(arr) contains free spots as > pointed by the index > > >> values stored at the position from 1 to arr[0]. Insertion > now only takes a > > >> constant time. Hence this has contributed in running > monkey a bit cheaper. > > >> Similar modifications are in progress, should help monkey > run more and more > > >> faster . :) > > >> > > >> Below are the results > > >> > > >> Output I got for running with "siege -c 300 -t 30S > 127.0.01:2001", > > >> > > >> //WITH CONSTANT TIME INSERTION > > >> Transactions: 18051 hits > > >> Availability: 100.00 % > > >> Elapsed time: 29.96 secs > > >> Data transferred: 23.48 MB > > >> Response time: 0.00 secs > > >> Transaction rate: 602.50 trans/sec > > >> Throughput: 0.78 MB/sec > > >> Concurrency: 2.30 > > >> Successful transactions: 18051 > > >> Failed transactions: 0 > > >> Longest transaction: 0.23 > > >> Shortest transaction: 0.00 > > >> > > >> ============================================ > > >> > > >> //EARLIER > > >> Transactions: 17711 hits > > >> Availability: 100.00 % > > >> Elapsed time: 30.01 secs > > >> Data transferred: 23.04 MB > > >> Response time: 0.00 secs > > >> Transaction rate: 590.17 trans/sec > > >> Throughput: 0.77 MB/sec > > >> Concurrency: 1.18 > > >> Successful transactions: 17711 > > >> Failed transactions: 0 > > >> Longest transaction: 0.17 > > >> Shortest transaction: 0.00 > > >> > > >> i had taken output for each case just after a fresh > restart. Reason for only > > >> ~600 trans/sec is that it was run ec2 t1.small instance. > > >> > > >> Thanks & Regards, > > >> mahesh gondi > > >> > > >> _______________________________________________ > > >> Monkey mailing list > > >> [email protected] > > >> http://lists.monkey-project.com/listinfo/monkey > > >> > > > > > > > > > > > > -- > > > Eduardo Silva > > > http://edsiper.linuxchile.cl > > > http://www.monkey-project.com > > > _______________________________________________ > > > Monkey mailing list > > > [email protected] > > > http://lists.monkey-project.com/listinfo/monkey > > > > _______________________________________________ > > Monkey mailing list > > [email protected] > > http://lists.monkey-project.com/listinfo/monkey > > > > > _______________________________________________ > Monkey mailing list > [email protected] > http://lists.monkey-project.com/listinfo/monkey > > _______________________________________________ Monkey mailing list [email protected] http://lists.monkey-project.com/listinfo/monkey
