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Re: fs-rep-sharing branch

From: Listman <listman_at_burble.net>
Date: Wed, 22 Oct 2008 02:12:45 -0700

On Oct 22, 2008, at 12:42 AM- Oct 22, 2008, Ivan Zhakov wrote:

> On Wed, Oct 22, 2008 at 10:29 AM, David Glasser
> <glasser_at_davidglasser.net> wrote:
>> On Tue, Oct 21, 2008 at 9:39 PM, Listman <listman_at_burble.net> wrote:
>>>
>>> On Oct 21, 2008, at 8:05 PM- Oct 21, 2008, Greg Stein wrote:
>>>
>>>> After you've changed the editor API, the wc_entry_t structure,
>>>> migrated all old clients over to svn_checksum_t, and then
>>>> switched the
>>>> storage defaults over to sh1, *then* we can talk about "an easy
>>>> switch".
>>>>
>>>> The simple fact is that we're going to be running around with md5
>>>> checksums in hand for a long while. OR we double-compute, and I'm
>>>> not
>>>> willing to burn that much CPU to satisfy somebody's misguided
>>>> preconception about md5 collisions. And double-compute generally
>>>> means
>>>> that we *carry around* both checkums. You wanna update all the APIs
>>>> for that, too?
>>>>
>>>
>>> +1 (on gregs position for this issue)
>>>
>>> lets not introduce more performance overheads based on a corner
>>> case.
>>>
>>> svn as it stands is way toooo slooow folks... please don't get
>>> distracted
>>> from
>>> that fact. i'm dealing with 20 minutes commits, 15 minute status
>>> checks etc
>>> and my
>>> users want to know why...
>>>
>>> also, svn already does way too many checksums from what i've been
>>> able to
>>> decipher.
>>
>> Well, if all you care about is speed, then revert the fsfs rep-
>> sharing
>> code entirely... it makes FSFS strictly less correct and presumably
>> strictly slower, bringing only a space benefit which (for FSFS)
>> appears to not be that large.
>>
> I agree with David: Subversion reliability is much more important than
> speed. Also I do not understand why we so care about disk space for
> repository: disk space is very cheap and become cheaper every day.
> Think that priority list should be:
> - Reliability
> - Speed (CPU/memory usage)
> - Disk space

with todays SVN performance anyone with a need for centralized DM and
large
data-sets would be better off using P4.

If SVN isn't reliable we lose, but if SVN is so slow that users aren't
efficient and
get frustrated we still lose.

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Received on 2008-10-22 11:13:03 CEST

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