I thought I heard that the additional translation tables involved for 64-bit address made DAT take longer. Whether that involved additional pipeline stages I don't know.
I have not seen any documentation that the same instruction that doesn't involve addresses takes long under 64-bit vs. 31-bit, like AGR, AGFI, LGHR, etc. On 2024-06-04 8:00 p.m., Ed Jaffe wrote:
EXTERNAL EMAIL ALERT This email originated from outside of DataKinetics. Do not click links or open any attachments unless you both recognize the sender, and know the content is safe. I remember hearing years ago from IBM that 64-bit mode programs tended to run slightly slower than those running in 31-bit mode. At the time, I assumed the reason was that programs using 8-byte pointers and integer values use more cache lines and 4K pages/frames than programs using 4-byte values. However, in a recent discussion we wondered if perhaps the "grande" instructions that operate on the full 64-bits of a register might also run a tiny bit slower than their counterpart instructions that operate only on the low halves of the registers. Wondering if anyone can shed some authoritative light on this topic... -- Phoenix Software International Edward E. Jaffe 831 Parkview Drive North El Segundo, CA 90245 https://www.phoenixsoftware.com/ -------------------------------------------------------------------------------- This e-mail message, including any attachments, appended messages and the information contained therein, is for the sole use of the intended recipient(s). If you are not an intended recipient or have otherwise received this email message in error, any use, dissemination, distribution, review, storage or copying of this e-mail message and the information contained therein is strictly prohibited. If you are not an intended recipient, please contact the sender by reply e-mail and destroy all copies of this email message and do not otherwise utilize or retain this email message or any or all of the information contained therein. Although this email message and any attachments or appended messages are believed to be free of any virus or other defect that might affect any computer system into which it is received and opened, it is the responsibility of the recipient to ensure that it is virus free and no responsibility is accepted by the sender for any loss or damage arising in any way from its opening or use.
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