From: Jeff Moyer <jmoyer@redhat.com>
To: Tao Ma <tm@tao.ma>
Cc: linux-kernel@vger.kernel.org, Jens Axboe <jaxboe@fusionio.com>
Subject: Re: [PATCH] blktrace: Remove blk_fill_rwbs_rq.
References: <1299137380-4119-1-git-send-email-tm@tao.ma>
Date: Thu, 03 Mar 2011 10:02:49 -0500
In-Reply-To: <1299137380-4119-1-git-send-email-tm@tao.ma> (Tao Ma's message of
	"Thu, 3 Mar 2011 15:29:40 +0800")
Message-ID: <x49k4ggs0va.fsf@segfault.boston.devel.redhat.com>
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Tao Ma <tm@tao.ma> writes:

> From: Tao Ma <boyu.mt@taobao.com>
>
> If we enable trace events to trace block actions, We use
> blk_fill_rwbs_rq to analyze the corresponding actions
> in request's cmd_flags, but we only choose the minor 2 bits
> from it, so most of other flags(e.g, REQ_SYNC) are missing.
> For example, with a sync write we get:
> write_test-2409  [001]   160.013869: block_rq_insert: 3,64 W 0 () 258135 + 8 [write_test]
>
> Since now we have integrated the flags of both bio and request,
> it is safe to pass rq->cmd_flags directly to blk_fill_rwbs and
> blk_fill_rwbs_rq isn't needed any more.
>
> With this patch, after a sync write we get:
> write_test-2417  [000]   226.603878: block_rq_insert: 3,64 WS 0 () 258135 + 8 [write_test]

Looks good to me.  It looks like the limited number of flags passed
through was simply an oversight (going back even to when the bio and
request flags were not merged, there was still special casing for
discard, at least).

Anywho...

Acked-by: Jeff Moyer <jmoyer@redhat.com>
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