Date: Wed, 10 Jun 1998 11:23:04 +1000 From: Bruce Evans <bde@zeta.org.au> To: ache@nagual.pp.ru, bde@FreeBSD.ORG Cc: current@FreeBSD.ORG Subject: Re: PIPE_BUF? Message-ID: <199806100123.LAA06267@godzilla.zeta.org.au>
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>>From sys/syslimits.h: > >#define PIPE_BUF 512 /* max bytes for atomic pipe >writes */ ^^^ > >Is it still true? If not, we should change it to _real_ value since some >software (like apache) depends on it. Yes. In 2.2, it really shouldn't be defined, since the max differs for ordinary pipes (they use PIPE_MAX = 512) and fifos (they use the default socket sb_lowat = MCLBYTES = 2048). However, applications can't tell that a too-small value is too small, since the system is not required to gratuitously make larger writes _non_ atomic. A smaller value is just more efficient for writers than don't care about atomicicity (since the system is less constrained), and less efficient and more restrictive for writers that do care (since they must send tinygrams). Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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