By: David Kanter (dkanter.delete@this.realworldtech.com), April 28, 2012 5:29 am
Room: Moderated Discussions
hcl64 (mario.smarq@gmail.com) on 4/27/12 wrote:
---------------------------
>David Kanter (dkanter@realworldtech.com) on 4/20/12 wrote:
>---------------------------
>>
>>You are correct that the caches are painfully slow, but that's not the reason why.
>>Frankly, I don't understand why the L1 is 4 cycles instead of 3. I REALLY don't
>>understand why the L2 cache is so slow (20 cycles, really??), because size alone
>>doesn't account for it. 12-14 cycles sounds much more reasonable.
>>
>>The L3 cache is also quite slow, in part because of the slow L2 and in part because
>>it runs at asynchronous to the cores. If you look at those two factors together
>>and assume a 14 cycle L2, you can probably cut the L3 latency down by ~10 cycles.
>>
>>
>>DK
>Good points. But isn't BD mostly asynchronous or semi->synchronous ?
No. You should read my article about Bulldozer.
http://www.realworldtech.com/page.cfm?ArticleID=RWT082610181333
Decoupled and asynchronous mean very different things. Asynchronous refers to frequency. Decoupled means there are buffers between stages. Those are two very different concepts and have very different implications for design.
DK
---------------------------
>David Kanter (dkanter@realworldtech.com) on 4/20/12 wrote:
>---------------------------
>>
>>You are correct that the caches are painfully slow, but that's not the reason why.
>>Frankly, I don't understand why the L1 is 4 cycles instead of 3. I REALLY don't
>>understand why the L2 cache is so slow (20 cycles, really??), because size alone
>>doesn't account for it. 12-14 cycles sounds much more reasonable.
>>
>>The L3 cache is also quite slow, in part because of the slow L2 and in part because
>>it runs at asynchronous to the cores. If you look at those two factors together
>>and assume a 14 cycle L2, you can probably cut the L3 latency down by ~10 cycles.
>>
>>
>>DK
>Good points. But isn't BD mostly asynchronous or semi->synchronous ?
No. You should read my article about Bulldozer.
http://www.realworldtech.com/page.cfm?ArticleID=RWT082610181333
Decoupled and asynchronous mean very different things. Asynchronous refers to frequency. Decoupled means there are buffers between stages. Those are two very different concepts and have very different implications for design.
DK
Topic | Posted By | Date |
---|---|---|
Phoronix tests GCC compiler flags and Bulldozer. | I.S.T. | 2012/04/19 02:05 AM |
Single page view? | David Kanter | 2012/04/19 07:59 AM |
Single page view? | wainwright | 2012/04/19 08:22 AM |
Single page view? | slothrop | 2012/04/19 08:23 AM |
Single page view? | David Kanter | 2012/04/19 08:31 AM |
Single page view? | EduardoS | 2012/04/19 02:12 PM |
Is there a single page view option for RWT articles? | anon | 2012/04/19 08:27 AM |
Single page view? | Del | 2012/04/19 08:36 AM |
Single page view? | slacker | 2012/04/19 02:56 PM |
Single page view? | Del | 2012/04/22 05:09 AM |
Single page view? | David Kanter | 2012/04/22 08:38 AM |
Single page view? | Del | 2012/04/23 12:22 AM |
Single page view? | Michael S | 2012/04/19 12:30 PM |
Single page view? | Ungo | 2012/04/19 01:25 PM |
Single page view? | Foo_ | 2012/04/19 11:17 PM |
Single page view? | James | 2012/04/20 03:01 AM |
There are ads on the web? | JJB | 2012/04/20 03:32 AM |
What a bunch of freeloaders (NT) | slacker | 2012/04/20 12:44 PM |
So are you, probably | iz | 2012/04/21 03:41 AM |
Impression ad revenue | Paul A. Clayton | 2012/04/21 05:44 AM |
So are you, probably | slacker | 2012/04/21 12:09 PM |
So are you, probably | David Kanter | 2012/04/22 08:41 AM |
So are you, probably | iz | 2012/04/22 02:57 PM |
So are you, probably | Doug Siebert | 2012/04/22 11:37 AM |
Aha! | David Kanter | 2012/04/22 02:45 PM |
Aha! | bakaneko | 2012/04/22 07:49 PM |
So are you, probably | iz | 2012/04/22 02:48 PM |
That's not how the business works... | David Kanter | 2012/04/22 04:31 PM |
That's not how the business works... | iz | 2012/04/23 12:49 AM |
So are you, probably | slacker | 2012/04/22 10:31 PM |
back to phoronix | Michael S | 2012/04/23 01:07 AM |
So are you, probably | iz | 2012/04/23 02:29 AM |
Membership at RWT | David Kanter | 2012/04/23 10:24 AM |
So are you, probably | Jukka Larja | 2012/04/27 07:59 AM |
So, what do people think of these numbers> | I.S.T. | 2012/04/19 06:34 PM |
So, what do people think of these numbers> | Linus Torvalds | 2012/04/20 07:34 AM |
So, what do people think of these numbers> | Kira | 2012/04/20 08:18 AM |
So, what do people think of these numbers> | Linus Torvalds | 2012/04/20 09:05 AM |
So, what do people think of these numbers> | Doug Siebert | 2012/04/20 08:00 PM |
So, what do people think of these numbers> | Megol | 2012/04/21 08:05 AM |
So, what do people think of these numbers> | Linus Torvalds | 2012/04/21 12:11 PM |
Most problems are fixed... | Megol | 2012/04/24 06:00 AM |
So, what do people think of these numbers> | bakaneko | 2012/04/20 10:16 AM |
So, what do people think of these numbers> | bakaneko | 2012/04/20 10:37 AM |
So, what do people think of these numbers> | Linus Torvalds | 2012/04/20 12:24 PM |
So, what do people think of these numbers> | Joel | 2012/04/20 01:59 PM |
So, what do people think of these numbers> | Kira | 2012/04/20 02:32 PM |
So, what do people think of these numbers> | EduardoS | 2012/04/20 03:00 PM |
Bulldozer's Oddities. | Joel | 2012/04/20 03:54 PM |
In defense of Bulldozer's Oddities | David Kanter | 2012/04/20 04:32 PM |
In defense of Bulldozer's Oddities | Exophase | 2012/04/20 06:11 PM |
In defense of Bulldozer's Oddities | EduardoS | 2012/04/20 06:46 PM |
In defense of Bulldozer's Oddities | Exophase | 2012/04/20 07:18 PM |
In defense of Bulldozer's Oddities | anonymous | 2012/04/20 10:26 PM |
In defense of Bulldozer's Oddities | JJB | 2012/04/20 10:34 PM |
In defense of Bulldozer's Oddities | imaxx | 2012/04/21 06:21 AM |
In defense of Bulldozer's Oddities | Michael S | 2012/04/21 09:42 AM |
Bulldozer's integer execution units | David Kanter | 2012/04/25 03:29 PM |
Bulldozer's integer execution units | Exophase | 2012/04/26 11:17 AM |
Bulldozer's integer execution units | anonymous | 2012/04/26 02:15 PM |
Bulldozer's integer execution units | EduardoS | 2012/04/26 02:40 PM |
Bulldozer's integer execution units | Foo_ | 2012/04/27 07:21 AM |
Bulldozer's integer execution units | Megol | 2012/04/27 12:38 PM |
Bulldozer's integer execution units | EduardoS | 2012/04/26 02:47 PM |
Bulldozer's integer execution units | Exophase | 2012/04/26 04:02 PM |
Bulldozer's integer execution units | EduardoS | 2012/04/26 05:03 PM |
Bulldozer's integer execution units | Exophase | 2012/04/26 05:24 PM |
Bulldozer's integer execution units | EduardoS | 2012/04/26 06:18 PM |
Bulldozer's cache memory performance | Heikki Kultala | 2012/04/28 12:18 AM |
Bulldozer's cache memory performance | EduardoS | 2012/04/28 09:06 AM |
Bulldozer's integer execution units | David Kanter | 2012/04/26 03:03 PM |
Bulldozer's integer execution units | Exophase | 2012/04/26 03:59 PM |
Bulldozer's integer execution units | David Kanter | 2012/04/26 09:53 PM |
Bulldozer's integer execution units | Exophase | 2012/04/27 07:42 AM |
Bulldozer's integer execution units | David Kanter | 2012/04/27 10:06 AM |
Bulldozer's integer execution units | EduardoS | 2012/04/27 12:27 PM |
K8 divided pipelines? | Paul A. Clayton | 2012/04/27 12:59 PM |
Bulldozer's integer execution units | Michael S | 2012/04/27 03:37 AM |
Bulldozer's integer execution units | Exophase | 2012/04/27 07:33 AM |
Bulldozer's integer execution units | anonymous | 2012/04/27 08:03 AM |
Renaming Flags | Konrad Schwarz | 2012/04/27 02:04 AM |
Renaming Flags | none | 2012/04/27 03:03 AM |
Renaming Flags | Megol | 2012/04/27 11:42 AM |
Bulldozer's integer execution units | hcl64 | 2012/04/27 03:31 PM |
VEX supports 3+ operands. FPU have renaming already(NT) | Megol | 2012/04/28 07:20 AM |
In defense of Bulldozer's Oddities | Linus Torvalds | 2012/04/21 11:26 AM |
Thanks for the lesson | JJB | 2012/04/21 01:23 PM |
Side note.. | Linus Torvalds | 2012/04/21 01:57 PM |
In defense of Bulldozer's Oddities | Exophase | 2012/04/21 11:13 AM |
In defense of Bulldozer's Oddities | EduardoS | 2012/04/21 11:53 AM |
In defense of Bulldozer's Oddities | Gionatan Danti | 2012/04/21 11:42 AM |
In defense of Bulldozer's Oddities | hcl64 | 2012/04/27 04:07 PM |
In defense of Bulldozer's Oddities | David Kanter | 2012/04/28 05:29 AM |
In defense of Bulldozer's Oddities | hcl64 | 2012/04/28 01:44 PM |
In defense of Bulldozer's Oddities | David Kanter | 2012/04/28 08:42 PM |
In defense of Bulldozer's Oddities | hcl64 | 2012/04/28 09:39 PM |
Bulldozer's Oddities. | EduardoS | 2012/04/20 05:05 PM |
Bulldozer's Oddities. | anon | 2012/04/20 07:32 PM |
Bulldozer's Oddities. | EduardoS | 2012/04/21 11:37 AM |
Bulldozer's Oddities. | anon | 2012/04/21 09:16 PM |
Bulldozer's Oddities. | EduardoS | 2012/04/21 09:43 PM |
Bulldozer's Oddities. | anon | 2012/04/22 01:09 AM |
Bulldozer's Oddities. | EduardoS | 2012/04/22 12:57 PM |
Bulldozer's Oddities. | anon | 2012/04/22 03:17 PM |
Bulldozer's Oddities. | EduardoS | 2012/04/22 04:05 PM |
Bulldozer's Oddities. | anon | 2012/04/22 04:42 PM |
Bulldozer's Oddities. | anon | 2012/04/22 05:01 PM |
Bulldozer's Oddities. | EduardoS | 2012/04/22 09:28 PM |
Bulldozer's Oddities. | anon | 2012/04/22 10:05 PM |
Bulldozer's isn't bad. | a reader | 2012/04/21 09:01 AM |
Bulldozer's isn't bad. | Kira | 2012/04/21 10:29 AM |
Bulldozer's isn't bad. | hcl64 | 2012/04/27 04:58 PM |
Bulldozer's isn't bad. | anon | 2012/04/27 05:16 PM |
Bulldozer's isn't bad. | hcl64 | 2012/04/27 06:33 PM |
Bulldozer's isn't bad. | rwessel | 2012/04/27 10:12 PM |
Bulldozer's isn't bad. | EduardoS | 2012/04/28 08:29 AM |
Bulldozer's isn't bad. | EduardoS | 2012/04/28 08:30 AM |
Bulldozer's isn't bad. | Michael S | 2012/04/28 11:36 AM |
Bulldozer is made for SPEC fp | Pelle-48 | 2012/04/21 10:41 AM |
Bulldozer's Oddities. | mpx | 2012/04/22 02:47 AM |
Bulldozer's Oddities. | EduardoS | 2012/04/22 12:57 PM |
Bulldozer's Oddities. | mpx | 2012/04/23 06:04 AM |
Bulldozer's Oddities. | Eric | 2012/04/23 11:33 AM |
Bulldozer's Oddities. | EduardoS | 2012/04/23 01:22 PM |
Bulldozer's Oddities. | Eric | 2012/04/23 06:30 PM |
Bulldozer's Oddities. | hcl64 | 2012/04/27 05:16 PM |
Bulldozer's Oddities. | Y | 2012/04/25 03:34 AM |
Bulldozer's IDIV | Heikki Kultala | 2012/04/27 09:56 PM |
Bulldozer's IDIV | Y | 2012/04/30 12:51 AM |
Bulldozer's IDIV | EduardoS | 2012/04/30 04:39 AM |
Bulldozer's IDIV | P3Dnow | 2012/05/08 12:23 AM |
Bulldozer's IDIV | Exophase | 2012/05/08 06:37 AM |
Bulldozer's Oddities. | EduardoS | 2012/04/23 01:15 PM |
Clustered MT as SMT for high frequency | Paul A. Clayton | 2012/04/20 03:10 PM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/27 11:56 PM |
Clustered MT as SMT for high frequency | anonymous | 2012/04/28 12:43 AM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/28 01:59 PM |
Clustered MT as SMT for high frequency | anonymous | 2012/04/28 07:45 PM |
Clustered MT as SMT for high frequency | anon | 2012/04/28 01:13 AM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/28 02:23 PM |
Clustered MT as SMT for high frequency | anon | 2012/04/28 05:19 PM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/28 06:58 PM |
Clustered MT as SMT for high frequency | David Kanter | 2012/04/28 05:38 AM |
Guessed meaning of "strong dependency model" | Paul A. Clayton | 2012/04/28 06:24 AM |
Guessed meaning of "strong dependency model" | EduardoS | 2012/04/28 08:46 AM |
*Right meaning* about "strong dependency model" | hcl64 | 2012/04/28 03:59 PM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/28 03:24 PM |
Clustered MT as SMT for high frequency | anonymous | 2012/04/28 07:50 PM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/28 08:47 PM |
SNB width | David Kanter | 2012/04/28 08:48 PM |
SNB width | hcl64 | 2012/04/29 01:24 AM |
Clustered MT as SMT for high frequency | David Kanter | 2012/04/28 08:56 PM |
Clustered MT as SMT for high frequency | hcl64 | 2012/04/28 10:44 PM |
SOI, FD vs. PD | David Kanter | 2012/04/29 06:19 AM |
SOI, FD vs. PD | hcl64 | 2012/04/29 04:31 PM |
SOI, FD vs. PD | David Kanter | 2012/04/29 10:26 PM |
SOI, FD vs. PD | hcl64 | 2012/04/30 07:08 AM |
SOI, FD vs. PD | David Kanter | 2012/04/30 08:59 AM |
SOI, FD vs. PD | hcl64 | 2012/04/30 05:10 PM |
SOI, FD vs. PD | David Kanter | 2012/04/30 05:32 PM |
SOI, FD vs. PD | hcl64 | 2012/04/30 09:47 PM |
SOI, FD vs. PD | David Kanter | 2012/05/01 01:24 AM |
SOI, FD vs. PD | hcl64 | 2012/05/01 04:46 AM |
SOI, FD vs. PD | hcl64 | 2012/05/01 05:37 AM |
SOI, FD vs. PD | David Kanter | 2012/05/01 07:19 AM |
SOI, FD vs. PD | hcl64 | 2012/05/01 06:39 AM |
PD-SOI | David Kanter | 2012/05/02 11:22 AM |
SOI, FD vs. PD | slacker | 2012/04/30 07:10 PM |
SOI, FD vs. PD | David Kanter | 2012/04/30 09:16 PM |
SOI, FD vs. PD | slacker | 2012/05/01 09:04 PM |
SOI, FD vs. PD | David Kanter | 2012/05/02 07:19 AM |
SOI, FD vs. PD | zou | 2012/05/02 11:23 AM |
Previous discussion of clustered MT | Paul A. Clayton | 2012/04/28 06:00 AM |
Previous discussion of clustered MT | hcl64 | 2012/04/28 08:38 PM |
Previous discussion of clustered MT | David Kanter | 2012/04/30 03:37 PM |
Previous discussion of clustered MT | hcl64 | 2012/04/30 06:24 PM |
Previous discussion of clustered MT | David Kanter | 2012/04/30 06:40 PM |
Previous discussion of clustered MT | hcl64 | 2012/05/01 08:15 AM |
Latency issues | David Kanter | 2012/05/02 11:01 AM |
So, what do people think of these numbers> | Megol | 2012/04/21 12:57 AM |