Gentoo Archives: gentoo-user

From: Alan McKinnon <alan.mckinnon@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Better CPU for compiling with gcc
Date: Tue, 10 Nov 2015 19:25:15
Message-Id: 5642444D.9050205@gmail.com
In Reply to: Re: [gentoo-user] Better CPU for compiling with gcc by Stanislav Nikolov
1 On 10/11/2015 21:07, Stanislav Nikolov wrote:
2 >
3 >
4 > On 11/10/2015 08:55 PM, Alan McKinnon wrote:
5 >> On 10/11/2015 20:37, Stanislav Nikolov wrote:
6 >>>
7 >>> On 11/10/2015 08:17 PM, Mick wrote:
8 >>>> On Tuesday 10 Nov 2015 17:47:08 Stanislav Nikolov wrote:
9 >>>>> Dear Gentoo users,
10 >>>>> I'm building a new PC. I have a budget of ~$550-$650. No GPU, no special
11 >>>>> case (I may use a card box), not even a hdd or ssd. So, as you can see,
12 >>>>> it's pretty much "get the best CPU and mobo/ram that are compatible with
13 >>>>> it". The problem is, which is the best one. By "best" I mean to compile
14 >>>>> shit fast. My laptop with 3rd gen i5 compiles firefox for 40 minutes on
15 >>>>> average.
16 >>>>>
17 >>>>> The most expensive Intel CPU is the skylake i7-6700k. But is it the best?
18 >>>>> Is there something from AMD that will perform even better? I can't find
19 >>>>> any benchmarks with AMD/Intel CPUs. And how much does the mobo matter?
20 >>>>> Will a cheap $30 400W PSU power that thing?
21 >>>>>
22 >>>>> Thanks
23 >>>> I don't (yet) own a i7-6700k, but my 6 year old laptop with (1st generation)
24 >>>> i7 Q720 @1.60GHz takes slightly less than yours:
25 >>>>
26 >>>> Sat Oct 3 14:35:40 2015 >>> www-client/firefox-38.3.0
27 >>>> merge time: 36 minutes and 53 seconds.
28 >>>>
29 >>>> Fri Nov 6 09:10:06 2015 >>> www-client/firefox-38.4.0
30 >>>> merge time: 38 minutes and 8 seconds.
31 >>>>
32 >>>>
33 >>>> In contrast a year old AMD A10-7850K APU is significantly faster:
34 >>>>
35 >>>> Sat Oct 3 19:40:48 2015 >>> www-client/firefox-38.3.0
36 >>>> merge time: 17 minutes and 42 seconds.
37 >>>>
38 >>>> Fri Nov 6 08:41:02 2015 >>> www-client/firefox-38.4.0
39 >>>> merge time: 18 minutes and 18 seconds.
40 >>>>
41 >>>>
42 >>>> I would also be interested to see compile times of more modern i7s and FXs,
43 >>>> but bear in mind that in single core operations Intel is these days
44 >>>> significantly better than AMD.
45 >>>>
46 >>> So, I shouldn't prepare for a 8x times faster compile time... :(
47 >>>
48 >>
49 >>
50 >> I can't help but think you are approaching this from the wrong perspective.
51 >>
52 >> Why exactly are you using compile times as your sole criterion? Are you
53 >> building a compile farm for Ubuntu? Running continuous integration tests
54 >> for LibreOffice [on a $600 budget in a cardboard box :-) ]?
55 >>
56 >> Or do you want emerge world to get it over with quicker?
57 >>
58 >> If the latter, you better rethink your priorities. In computing terms,
59 >> compilation is a rare event; launching apps is a common event; and
60 >> writing to the disk happens all the time. Optimize for the common case.
61 >>
62 >> A CPU never works in isolation, it is always part of a much larger
63 >> system, like disks, RAM and all possible kinds of I/O. The best CPU on
64 >> the market plugged into a POS motherboard will perform on emerge world
65 >> like a piece of shit - it will follow the weakest link.
66 >>
67 >> If you want to build a compiling machine, buy the best collection of
68 >> stuff that works together well and still fits the budget. If you want a
69 >> machine that you can use and be happy with, ignoree the temptation to
70 >> must have the biggest baddest fastest CU (you will never get to use all
71 >> that big bad fast) and invest rather in gobs of RAM and an SSD. Remember
72 >> that apps are launched many times more than they are compiled. Or put
73 >> another way, sacrifice compilation times t get something you can use.
74 >
75 > 8GB of RAM are waaay more than I use daily (several firefox tabs, nvim = 2Gb max), I have a pretty fast SSD too. Even buying 8GB RAM and a brand new SSD, I have > $450 left. Can I buy a AMD CPU that will get the job done faster than 6700k and/or cheaper?
76 >
77
78
79 That changes things. It wasn't obvious you already had RAM & SSD & stuff.
80
81 I'd first make sure I have a decent PSU - none of that crap puny
82 el-cheapo $300 shit (search list archives for 1000s of posts about dodgy
83 PSUs). Then split the difference between 8G RAM, a good CPU and an
84 excellent motherboard. You will use that extra RAM, and a motherboard
85 that ties all the bits together properly is much more cost-effective
86 than raw CPU grunt alone.
87
88 --
89 Alan McKinnon
90 alan.mckinnon@×××××.com

Replies

Subject Author
Re: [gentoo-user] Better CPU for compiling with gcc Dale <rdalek1967@×××××.com>