Re: performance of shell read loops

2016-03-13 Thread Joerg Sonnenberger
On Sat, Mar 12, 2016 at 10:17:26PM +0700, Robert Elz wrote: > | Actually I was wondering if there aren't more use cases for a "read > | until you find the following sequence" system call or just something > | specifiying a (simple) regular expression. > > I was too - but I suspect that the o

Re: performance of shell read loops

2016-03-13 Thread David Laight
On Sat, Mar 12, 2016 at 10:17:26PM +0700, Robert Elz wrote: > > | Actually I was wondering if there aren't more use cases for a "read > | until you find the following sequence" system call or just something > | specifiying a (simple) regular expression. > > I was too - but I suspect that th

Re: performance of shell read loops

2016-03-12 Thread Robert Elz
Date:Sat, 12 Mar 2016 14:50:59 +0100 From:Joerg Sonnenberger Message-ID: <20160312135059.ga27...@britannica.bec.de> | I'm not sure. A lot of shell processing also happens on real files. There are three cases that could work to improve this - when input is seekable,

Re: performance of shell read loops

2016-03-12 Thread Joerg Sonnenberger
On Sat, Mar 12, 2016 at 12:08:10PM +, David Laight wrote: > On Mon, Mar 07, 2016 at 04:09:06PM +0700, Robert Elz wrote: > > > > Then I ktrace'd it, and of course, the "read" builtin command is reading > > one character at a time. If you think about it just a litte, you will > > see that it m

Re: performance of shell read loops

2016-03-12 Thread David Laight
On Mon, Mar 07, 2016 at 04:09:06PM +0700, Robert Elz wrote: > > Then I ktrace'd it, and of course, the "read" builtin command is reading > one character at a time. If you think about it just a litte, you will > see that it must work that way (it is only permitted to take one line of > data from

Re: performance of shell read loops

2016-03-07 Thread Robert Elz
Date:Mon, 7 Mar 2016 05:21:35 + From:David Holland Message-ID: <20160307052135.ga7...@netbsd.org> | pretty bad! I thought I'd verify my assumption about echo, so modified (my already modified) script by simply removing the "echo". Not the same test at all, so

Re: performance of shell read loops

2016-03-07 Thread Robert Elz
Date:Mon, 7 Mar 2016 05:21:35 + From:David Holland Message-ID: <20160307052135.ga7...@netbsd.org> | Today it came up (in the context of something Christos did) that shell | read loops are horribly, horribly slow. I had been intending to look at shell performa