From jik@kamens.brookline.ma.us Wed Feb 12 12:21:25 1997
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Date: Wed, 12 Feb 1997 12:25:13 -0500
From: "Jonathan I. Kamens" <jik@kamens.brookline.ma.us>
Reply-To: jik@cam.ov.com
To: krb5-bugs@MIT.EDU
Cc: jik@cam.ov.com
Subject: rcache speedup via removing fsync() call
X-Send-Pr-Version: 3.99
after every entry it writes into the replay cache.
This has very little, if any, benefit, since once the data is
written, it will be flushed to disk soon enough unless the machine
crashes, and if the machine crashes, it could just as easily crash
before the fsync(). And besides, it'll probably take more than five
minutes to come back up, this making the replay cache irrelevant :-).
It does, however, have a significant downside -- it makes
persistent applications run slower (without the fsync, a GSS-API
context initiation takes 10ms less) and thrashes the disk
unnecessarily when an application is receiving frequent Kerberos
requests.
In short, I think the fsync() isn't necessary and should be
removed.
+++ krb5-1.0/src/lib/krb5/rcache/rc_dfl.c Wed Feb 12 09:37:11 1997
@@ -523,13 +523,6 @@
{
return krb5_rc_dfl_expunge(context, id);
}
-#ifndef NOIOSTUFF
- else
- {
- if (krb5_rc_io_sync(context, &t->d))
- return KRB5_RC_IO;
- }
-#endif
return 0;
}
From: Tom Yu <tlyu@MIT.EDU>
To: Unassigned Problem Report <krb5-unassigned@RT-11.MIT.EDU>
Cc: krb5-bugs@MIT.EDU
Subject: Re: krb5-libs/372: rcache speedup via removing fsync() call
Date: Wed, 12 Feb 1997 17:12:46 -0500
`Tom Yu' made changes to this PR.
*** /tmp/gnatsb0032m Wed Feb 12 17:11:24 1997
--- /tmp/gnatsc0032m Wed Feb 12 17:12:34 1997
***************
*** 11,22 ****
Reply-To: jik@cam.ov.com
To: krb5-bugs@MIT.EDU
Cc: jik@cam.ov.com
! Subject: Replay cache shouldn't fsync() after every item is written
X-Send-Pr-Version: 3.99
Reply-To: jik@cam.ov.com
To: krb5-bugs@MIT.EDU
Cc: jik@cam.ov.com
! Subject: rcache speedup via removing fsync() call
X-Send-Pr-Version: 3.99
From: "Jonathan I. Kamens" <jik@cam.ov.com>
To: krb5-bugs@MIT.EDU
Cc: Subject: Re: krb5-libs/372: replay cache code shouldn't fsync after every entry added to the cache
Date: Mon, 11 Aug 1997 15:58:49 -0400
Has this patch been merged back into the main branch of the MIT source
tree? Will it be included in the next MIT release?
Thanks,
jik
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id MAA23021; Wed, 12 Feb 1997 12:25:13 -0500
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Date: Wed, 12 Feb 1997 12:25:13 -0500
From: "Jonathan I. Kamens" <jik@kamens.brookline.ma.us>
Reply-To: jik@cam.ov.com
To: krb5-bugs@MIT.EDU
Cc: jik@cam.ov.com
Subject: rcache speedup via removing fsync() call
X-Send-Pr-Version: 3.99
Show quoted text
>Number: 372
>Category: krb5-libs
>Synopsis: rcache speedup via removing fsync() call
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: krb5-unassigned
>State: open
>Class: sw-bug
>Submitter-Id: unknown
>Arrival-Date: Wed Feb 12 12:22:01 EST 1997
>Last-Modified: Mon Aug 11 15:59:00 EDT 1997
>Originator: Jonathan I. Kamens
>Organization:
OpenVision Technologies, Inc.>Category: krb5-libs
>Synopsis: rcache speedup via removing fsync() call
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: krb5-unassigned
>State: open
>Class: sw-bug
>Submitter-Id: unknown
>Arrival-Date: Wed Feb 12 12:22:01 EST 1997
>Last-Modified: Mon Aug 11 15:59:00 EDT 1997
>Originator: Jonathan I. Kamens
>Organization:
Show quoted text
>Release: 1.0
>Environment:
N/A>Environment:
Show quoted text
>Description:
The replay cache code calls fsync() to flush data to diskafter every entry it writes into the replay cache.
This has very little, if any, benefit, since once the data is
written, it will be flushed to disk soon enough unless the machine
crashes, and if the machine crashes, it could just as easily crash
before the fsync(). And besides, it'll probably take more than five
minutes to come back up, this making the replay cache irrelevant :-).
It does, however, have a significant downside -- it makes
persistent applications run slower (without the fsync, a GSS-API
context initiation takes 10ms less) and thrashes the disk
unnecessarily when an application is receiving frequent Kerberos
requests.
In short, I think the fsync() isn't necessary and should be
removed.
Show quoted text
>How-To-Repeat:
Show quoted text
>Fix:
--- krb5-1.0/src/lib/krb5/rcache/rc_dfl.c Mon Nov 18 19:36:57 1996+++ krb5-1.0/src/lib/krb5/rcache/rc_dfl.c Wed Feb 12 09:37:11 1997
@@ -523,13 +523,6 @@
{
return krb5_rc_dfl_expunge(context, id);
}
-#ifndef NOIOSTUFF
- else
- {
- if (krb5_rc_io_sync(context, &t->d))
- return KRB5_RC_IO;
- }
-#endif
return 0;
}
Show quoted text
>Audit-Trail:
From: Tom Yu <tlyu@MIT.EDU>
To: Unassigned Problem Report <krb5-unassigned@RT-11.MIT.EDU>
Cc: krb5-bugs@MIT.EDU
Subject: Re: krb5-libs/372: rcache speedup via removing fsync() call
Date: Wed, 12 Feb 1997 17:12:46 -0500
`Tom Yu' made changes to this PR.
*** /tmp/gnatsb0032m Wed Feb 12 17:11:24 1997
--- /tmp/gnatsc0032m Wed Feb 12 17:12:34 1997
***************
*** 11,22 ****
Reply-To: jik@cam.ov.com
To: krb5-bugs@MIT.EDU
Cc: jik@cam.ov.com
! Subject: Replay cache shouldn't fsync() after every item is written
X-Send-Pr-Version: 3.99
Show quoted text
>Number: 372
>Category: krb5-libs
! >Synopsis: Replay cache shouldn't fsync() after every item is written>Category: krb5-libs
Show quoted text
>Confidential: no
>Severity: non-critical
>Priority: low
--- 11,22 ---->Severity: non-critical
>Priority: low
Reply-To: jik@cam.ov.com
To: krb5-bugs@MIT.EDU
Cc: jik@cam.ov.com
! Subject: rcache speedup via removing fsync() call
X-Send-Pr-Version: 3.99
Show quoted text
>Number: 372
>Category: krb5-libs
! >Synopsis: rcache speedup via removing fsync() call>Category: krb5-libs
Show quoted text
>Confidential: no
>Severity: non-critical
>Priority: low
>Severity: non-critical
>Priority: low
From: "Jonathan I. Kamens" <jik@cam.ov.com>
To: krb5-bugs@MIT.EDU
Cc: Subject: Re: krb5-libs/372: replay cache code shouldn't fsync after every entry added to the cache
Date: Mon, 11 Aug 1997 15:58:49 -0400
Has this patch been merged back into the main branch of the MIT source
tree? Will it be included in the next MIT release?
Thanks,
jik
Show quoted text
>Unformatted: