Messages in this thread | | | Subject | Re: SMP read() stopping at memory page boundaries | From | Timo Sirainen <> | Date | Wed, 20 Jun 2007 19:57:02 +0300 |
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On Wed, 2007-06-20 at 09:22 -0700, Ray Lee wrote: > On 6/20/07, Timo Sirainen <tss@iki.fi> wrote: > > On Wed, 2007-06-20 at 17:52 +0300, Timo Sirainen wrote: > > > Sometimes read() returns only 4096 bytes. I'm locking the file, so I > > > don't think this should ever happen, right? > > man 2 read > > read() is always allowed to return less than you asked for. You need > to go back and ask for the rest. That's why people wrap read() and > write() in loops, and use those wrapped versions instead.
I thought this wouldn't happen when reading from local filesystems. Anyway, my real program was doing that, and it was still seeing partial data. But looks like I can't reproduce it in my test program with two pread()s, so I'll have to do some more debugging.
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