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Ciaran McCreesh wrote: |
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> On Wed, 25 Feb 2009 09:33:44 +0100 |
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> Alexis Ballier <aballier@g.o> wrote: |
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>> That sounds like an implementation detail that you could solve by |
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>> using something else than a flat file database for metadata if |
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>> open()/read() calls are the slow part. |
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> |
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> Metadata's shipped with the tree. It's a PMS detail. |
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> |
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> If we didn't care about package manager performance, we wouldn't be |
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> shipping metadata with the tree at all... |
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> |
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>>>> I would be very surprised if that "2 times" factor happens to be |
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>>>> true, because finding a string in a file is an order of magnitude |
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>>>> simpler than sourcing said file with bash. Moreover this doesn't |
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>>>> take into account disk and os cache. |
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>>> No no no. *Opening* the file is the slow part, not searching. The |
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>>> file wouldn't otherwise be opened at all. |
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>> Thus the only drawback is when you open a file, see there that you |
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>> can't handle the eapi, then close it and open an older one. |
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> |
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> Uh. No. The drawback is that you're opening around ten thousand files |
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> that would otherwise not be opened. That's a huge cost. |
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> |
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|
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Huge cost... |
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|
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emerge -uDp world (cold os cache) |
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|
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real 1m10.353s |
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user 0m17.077s |
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sys 0m0.440s |
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|
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with eapitool getting the eapi before sourcing. |
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|
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real 1m10.636s |
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user 0m16.941s |
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sys 0m0.368s |
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|
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cold cache, no metadata available |
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|
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real 6m23.106s |
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user 3m32.141s |
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sys 1m50.855s |
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|
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with eapitool |
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|
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real 6m26.564s |
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user 3m31.853s |
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sys 1m50.511s |
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|
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|
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I'd rather see more people backing their ideas with numbers... |
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|
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lu |
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|
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-- |
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|
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Luca Barbato |
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Gentoo Council Member |
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Gentoo/linux Gentoo/PPC |
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http://dev.gentoo.org/~lu_zero |
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