Thank you does the number “GET” ahead I/o depend on Buffno
> On Mar 20, 2021, at 11:31 AM, Michael Stein <[email protected]> wrote: > > On Fri, Mar 19, 2021 at 03:35:39PM -0400, Joseph Reichman wrote: >> So this is what I will do >> >> I’ll do 3 reads in the first since i need to get myself going I’ll issue the >> WAIT using the ECB from the DECB > > Limiting the pending reads to 3 will limit the performance to worse > (or at least no better) than QSAM. > > You did set NCP to a value at least high enough for the number of > pending READs you would have at any time, right? > > Also keep in mind that you need to issue the wait/check on the > DECBs in exactly the same order as you did the READs. > > See the section "Using Overlapped I/O with BSAM" in DFSMS Using Data Sets > (in Chapter 22 Accessing Records). > >> Than when I finish processing that buffer and need to go to the second >> I/O I’ll issue a WAIT for that > > Unless you are reading multple files (multiple DCBs) at once (each with > their own group of pending READs) issuing WAIT before CHECK is just > wasted effort/CPU time. > > This is because you have to issue the CHECKs for each DCB in the order > you did the READs and they will complete in that order. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
