c - maxevents parameter in epoll_wait() and the events array size -


in epoll usage, following:

struct epoll_event ev,events[20]; epfd=epoll_create(256); 。。。 nfds=epoll_wait(epfd,events,40,500);

some articles saying maxevents parameter in epoll_wait (namely 40 in epoll_wait(epfd,events,40,500);) should not exceed size parameter in epoll_create(namely 256).

i think maxevents parameter should not exceed 20 in ev, events[20], because events can registered 20 events elements; otherwise, if there 40 sockets active, happen?

btw, if register more 20 sockets , there more 20 active events(sockets), events array events[20] has 20 events, happen?

at single call of epoll_wait you'll @ receive many events have room for, of course events don't lost if there more queued -- you'll them @ later call. since you'll calling epoll_wait in loop anyway, shouldn't issue @ all.

the 1 interesting consideration can think of when have multiple threads read same epoll-fd concurrently. in case size of event array determines how many events handled single thread (i.e. smaller number might give greater parallelism).


Comments

Post a Comment

Popular posts from this blog

Socket.connect doesn't throw exception in Android -

if put nonsense url no exception thrown , none of rest of code executed not rest of asynctask called method connects. try { socketcliente.connect(new inetsocketaddress("f", port), 2000); } catch (unknownhostexception e) { geterror("host doesn't exist"); return -1; } catch (ioexception e) { geterror("could not connect: host down"); return -1; } add catch statement. catch ( exception e ) { log.d(tag, e.getmessage(),e); toast.maketext(getapplicationcontext(), "unexpected error:" + e.getmessage(), toast.length_long).show(); } this write log , pop toast tell what's going on.
Read more

SPSS keyboard combination alters encoding -

my question not have programming practical issue on spss. accident keyword combination cannot remember because did not intend press changed encoding in spss , text in data in different language english shown small boxes. nevertheless, when kind of analysis performed different language text shown in output. does know reason? tried change encoding did not produce result. first, @ edit > options , see whether setting unicode or locale. might fix it. if have text in multiple languages, want unicode. otherwise, may have specific locale set wrong. can change set locale, need know locale want use.
Read more

iphone - How do I keep MDScrollView from truncating my row headers and making my cells look bad? -

Image
here's screenshot show describing: and relevant code: - (nsinteger)spreadview:(mdspreadview *)aspreadview numberofcolumnsinsection:(nsinteger)section{ return self.viewmodel.matrix.width - 1; } - (nsinteger)spreadview:(mdspreadview *)aspreadview numberofrowsinsection:(nsinteger)section{ return self.viewmodel.matrix.height - 1; } -(mdspreadviewcell *)spreadview:(mdspreadview *)aspreadview cellforrowatindexpath:(mdindexpath *)rowpath forcolumnatindexpath:(mdindexpath *)columnpath{ mdspreadviewcell *cell = [aspreadview dequeuereusablecellwithidentifier:@"infocell"]; if (cell == nil){ cell = [[[mdspreadviewcell alloc] initwithstyle:mdspreadviewcellstyledefault reuseidentifier:@"infocell"] autorelease]; } cell.textlabel.text = ((dtvendor *)self.vendors[rowpath.row]).name; return cell; } -(cgfloat)spreadview:(mdspreadview *)aspreadview heightforrowheaderinsection:(nsinteger)rowsection{ return 200; } -(cgfloat)spreadview:(mdspreadview...
Read more