Potential issue during MBA reset on AMD

[mdcornu]

MBA COS get reset to 0 by default. This may not be correct behavior on AMD platforms.

https://github.com/intel/intel-cmt-cat/blob/1e6ee29be038ca67cf8fe9760bf53d97dde849e3/lib/allocation.c#L1642

[babumoger]

Ok. Sure. Will investigate.

[babumoger]

Marcel, Yes. When I reset the MBA values(pqos -R), I see the MBA values are getting reset to 0. I expected it to go back to default values. Shouldn't we reset it to default maximum value(100 for Intel and 0x800 for AMD)? I am thinking this may be generic issue.

[tkanteck]

It doesn't seem to be a generic issue as the MBA reset works fine on Intel platforms

[babumoger]

Ok. got it. The reset values for Intel and AMD are different. For Intel, the reset value is 0 and for AMD reset value is 0x800. This patch should fix it. Will sent a pull request.

diff --git a/lib/allocation.c b/lib/allocation.c index d850c39..37b20f3 100644 --- a/lib/allocation.c +++ b/lib/allocation.c @@ -1632,6 +1632,8 @@ hw_alloc_reset(const enum pqos_cdp_config l3_cdp_cfg, */ for (j = 0; j < mba_id_num; j++) { unsigned core = 0;

• unsigned val = (m_cpu->vendor == PQOS_VENDOR_AMD)

• ? PQOS_MBA_MAX_AMD : 0;

                   ret = pqos_cpu_get_one_by_mba_id(m_cpu, mba_ids[j],
                                                    &core);

  @@ -1639,7 +1641,7 @@ hw_alloc_reset(const enum pqos_cdp_config l3_cdp_cfg, goto pqos_alloc_reset_exit;

                   ret = alloc_cos_reset(vconfig->mba_msr_reg,

• mba_cap->num_classes, core, 0);
• mba_cap->num_classes, core, val); if (ret != PQOS_RETVAL_OK) goto pqos_alloc_reset_exit; }

[kmabbasi]

Thanks Babu

Patch has been merged to master branch. Therefore, closing this issue now.

Thanks, Khawar