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Re: kernel.org mirroring (Re: [GIT PULL] MMC update)

From
HAH. Peter Anvin <hpa@zytor.com>
Date
Dec 9, 2006, 16:26 UTC
Message-ID
<457AE3A7.4080802@zytor.com>
In-Reply-To
<46a038f90612082134x38be9c8dgca6fe60c087bf100@mail.gmail.com>
Martin Langhoff wrote:
Show 26 quoted lines
> On 12/9/06, H. Peter Anvin <hpa@zytor.com> wrote:
>> Martin Langhoff wrote:
>> > I posted separately about those. And I've been mulling about whether
>> > the thundering herd is really such a big problem that we need to
>> > address it head-on.
>>
>> Uhm... yes it is.
> 
> Got some more info, discussion points or links to stuff I should read
> to appreciate why that is? I am trying to articulate why I consider it
> is not a high-payoff task, as well as describing how to tackle it.
> 
> To recap, the reasons it is not high payoff is that:
> 
> - the main benefit comes from being cacheable and able to revalidate
> the cache cheaply (with the ETags-based strategy discussed above)
> - highly distributed caches/proxies means we'll seldom see a true
> cold cache situation
> - we have a huge set of URLs which are seldom hit, and will never see
> a thundering anything
> - we have a tiny set of very popular URLs that are the key target for
> the thundering herd - (projects page, summary page, shortlog, fulllog)
> - but those are in the clear as soon as the caches are populated
> 
> Why do we have to take it head-on? :-)
> 

Because the primary failure scenario is timeout on the common queries due to excess parallel invocations under high I/O load resulting in catastrophic failure.

Previous: Martin LanghoffNext: H. Peter Anvin
Message 17 of 80 in “Re: kernel.org mirroring (Re: [GIT PULL] MMC update)”
  1. Linus TorvaldsDec 7, 2006
  2. H. Peter AnvinDec 7, 2006
  3. Olivier GalibertDec 7, 2006
  4. H. Peter AnvinDec 7, 2006
  5. Olivier GalibertDec 7, 2006
  6. H. Peter AnvinDec 7, 2006
  7. Jakub NarebskiDec 8, 2006
  8. Rogan DawesDec 8, 2006
  9. Jakub NarebskiDec 8, 2006
  10. Rogan DawesDec 8, 2006
  11. Jonas FonsecaDec 8, 2006
  12. Martin LanghoffDec 9, 2006
  13. H. Peter AnvinDec 9, 2006
  14. Martin LanghoffDec 9, 2006
  15. H. Peter AnvinDec 9, 2006
  16. Martin LanghoffDec 9, 2006
  17. H. Peter AnvinDec 9, 2006
  18. H. Peter AnvinDec 8, 2006
  19. Linus TorvaldsDec 8, 2006
  20. H. Peter AnvinDec 8, 2006
  21. Lars HjemliDec 8, 2006
  22. H. Peter AnvinDec 8, 2006
  23. Lars HjemliDec 8, 2006
  24. H. Peter AnvinDec 8, 2006
  25. rdaDec 10, 2006
  26. Jeff GarzikDec 8, 2006
  27. H. Peter AnvinDec 8, 2006
  28. Jeff GarzikDec 8, 2006
  29. Linus TorvaldsDec 8, 2006
  30. Michael K. EdwardsDec 8, 2006
  31. H. Peter AnvinDec 8, 2006
  32. Michael K. EdwardsDec 9, 2006
  33. H. Peter AnvinDec 9, 2006
  34. Linus TorvaldsDec 9, 2006
  35. H. Peter AnvinDec 9, 2006
  36. Michael K. EdwardsDec 9, 2006
  37. Jeff GarzikDec 9, 2006
  38. Martin LanghoffDec 9, 2006
  39. Jakub NarebskiDec 9, 2006
  40. Jeff GarzikDec 9, 2006
  41. Jakub NarebskiDec 9, 2006
  42. Jeff GarzikDec 9, 2006
  43. Jakub NarebskiDec 9, 2006
  44. Jeff GarzikDec 9, 2006
  45. Martin LanghoffDec 10, 2006
  46. Jakub NarebskiDec 10, 2006
  47. Jeff GarzikDec 10, 2006
  48. Jakub NarebskiDec 10, 2006
  49. Jeff GarzikDec 10, 2006
  50. Jakub NarebskiDec 10, 2006
  51. Linus TorvaldsDec 10, 2006
  52. Jakub NarebskiDec 10, 2006
  53. Linus TorvaldsDec 10, 2006
  54. Martin LanghoffDec 10, 2006
  55. Jeff GarzikDec 10, 2006
  56. Jeff GarzikDec 10, 2006
  57. H. Peter AnvinDec 10, 2006
  58. Jeff GarzikDec 10, 2006
  59. Jakub NarebskiDec 10, 2006
  60. Martin LanghoffDec 11, 2006
  61. Jakub NarebskiDec 11, 2006
  62. Martin LanghoffDec 11, 2006
  63. Linus TorvaldsDec 9, 2006
  64. H. Peter AnvinDec 9, 2006
  65. Martin LanghoffDec 10, 2006
  66. H. Peter AnvinDec 10, 2006
  67. Jakub NarebskiDec 12, 2006
  68. Steven GrimmDec 9, 2006
  69. Linus TorvaldsDec 7, 2006
  70. Shawn PearceDec 7, 2006
  71. Linus TorvaldsDec 7, 2006
  72. Michael K. EdwardsDec 7, 2006
  73. H. Peter AnvinDec 7, 2006
  74. Junio C HamanoDec 7, 2006
  75. H. Peter AnvinDec 7, 2006
  76. Junio C HamanoDec 7, 2006
  77. Jakub NarebskiDec 8, 2006
  78. Linus TorvaldsDec 9, 2006
  79. H. Peter AnvinDec 9, 2006
  80. Jeff GarzikDec 9, 2006

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