Bug 103073
| Summary: | hugepage documentation incorrect... | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 3 | Reporter: | Johnray Fuller <jrfuller> |
| Component: | kernel | Assignee: | Jason Baron <jbaron> |
| Status: | CLOSED CURRENTRELEASE | QA Contact: | Brian Brock <bbrock> |
| Severity: | high | Docs Contact: | |
| Priority: | medium | ||
| Version: | 3.0 | CC: | knoel |
| Target Milestone: | --- | ||
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2003-09-26 16:30:54 UTC | Type: | --- |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
|
Description
Johnray Fuller
2003-08-26 13:45:55 UTC
This is also not how I understand it: "Use the following command to dynamically allocate/deallocate hugepages: echo 20 > /proc/sys/vm/nr_hugepages This command will try to configure 20 hugepages in the system." I thought the value echoed is in megabytes and that this value is divided by the size of the hugepages (2, 4 or 256 depending on the kernel) to determine the total number of hugepages. So on an SMP x86 kernel, this command would create 10 hugepages. On a UP x86 kernel, this would create 5 hugepages, and on. Is my interpretation of this incorrect or is the documentation? J nr_hugepages is in 'page' units hugetlb_page is in MB units... for as3 we have the hugetlb_page interface So /proc/sys/vm/hugetlb_pool and /proc/sys/vm/nr_hugepages are not synonymous and function differently. But /proc/sys/vm/nr_hugepages is not present in Taroon. Are their plans to add /proc/sys/vm/hugetlb_pool to this kernel document? As it stands the inconsistency between the /proc chapter in the RG (http://intranet.corp.redhat.com/docs/taroon/rhel-rg-en/ch-proc.html) and this document are very confusing. I reference this document because it is the only thing that explains how to set up and use hugepages. Also, does hugetlb_page = hugetlb_pool? J first, yes i mean hugetlb_pool, not hugetlb_page. i think generally the Documentation directory in the kernel is understood to apply to the upstream kernel, and is superceded by any Red Hat documentation. But, i'm not sure this policy or understanding is explicitly laid out anywhere So this document is not going to be updated or ammended? We don't have the time to incorporate a Red Hat-specific version of this file before deadline into the RG. Is there any documentation online about the Red Hat implementation I can point to by chance? Finally, is everything else accurate in this document appart from the references to nr_hugepages? If so, I can put a disclaimer in the proc chapter highlighting that detail. J i don't think we're updating the the Documentation/vm/hugetlbpage.txt file. I think everything there is correct w/respect to Red Hat's implementation, except for the nr_hugepages, as you mentioned. The excerpt below is from the updated proc chapter, available online at the following URL: http://intranet.corp.redhat.com/docs/taroon/rhel-rg-en/s1-proc-directories.html#S3-PROC-SYS-VM "Refer to /usr/src/linux-2.4/Documentation/vm/hugetlbpage.txt for more information about configuring hugepages. Important Despite being mentioned in hugetlbpage.txt, the file /proc/sys/vm/nr_hugepages does not exist within Red Hat Enterprise Linux. Instead hugetlb_pool should be used to configure the number of hugepages available for the system. Also, it is important to remember that nr_hugepages uses hugepage units, while hugetlb_pool configures hugepages in megabytes." Is this sufficient? looks fine, i'm closing this |