From 4d01ece69f7b4d7bd56210e0f839944a91c5679f Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 17 May 2013 12:47:11 +0200 Subject: [PATCH] Update HOWTO and man page for thinktime blocks impact on queue depth Signed-off-by: Jens Axboe --- HOWTO | 8 ++++++-- fio.1 | 7 ++++++- 2 files changed, 12 insertions(+), 3 deletions(-) diff --git a/HOWTO b/HOWTO index 9b2edb37..794728f3 100644 --- a/HOWTO +++ b/HOWTO @@ -830,11 +830,15 @@ thinktime_spin=int to sleeping for the rest of the period specified by thinktime. -thinktime_blocks +thinktime_blocks=int Only valid if thinktime is set - control how many blocks to issue, before waiting 'thinktime' usecs. If not set, defaults to 1 which will make fio wait 'thinktime' usecs - after every block. + after every block. This effectively makes any queue depth + setting redundant, since no more than 1 IO will be queued + before we have to complete it and do our thinktime. In + other words, this setting effectively caps the queue depth + if the latter is larger. rate=int Cap the bandwidth used by this job. The number is in bytes/sec, the normal suffix rules apply. You can use rate=500k to limit diff --git a/fio.1 b/fio.1 index f54ea34b..91020b2e 100644 --- a/fio.1 +++ b/fio.1 @@ -702,7 +702,12 @@ Pretend to spend CPU time for given number of microseconds, sleeping the rest of the time specified by \fBthinktime\fR. Only valid if \fBthinktime\fR is set. .TP .BI thinktime_blocks \fR=\fPint -Number of blocks to issue before waiting \fBthinktime\fR microseconds. +Only valid if thinktime is set - control how many blocks to issue, before +waiting \fBthinktime\fR microseconds. If not set, defaults to 1 which will +make fio wait \fBthinktime\fR microseconds after every block. This +effectively makes any queue depth setting redundant, since no more than 1 IO +will be queued before we have to complete it and do our thinktime. In other +words, this setting effectively caps the queue depth if the latter is larger. Default: 1. .TP .BI rate \fR=\fPint -- 2.25.1