* Re: [PATCH] HUGETLBFS: Align memory request to multiple of huge page size to avoid underallocating. [not found] <1330351768-14874-1-git-send-email-steven.truelove@utoronto.ca> @ 2012-02-27 23:42 ` Andrew Morton 2012-02-28 2:55 ` Steven Truelove 0 siblings, 1 reply; 3+ messages in thread From: Andrew Morton @ 2012-02-27 23:42 UTC (permalink / raw) To: Steven Truelove; +Cc: wli, linux-kernel, linux-mm On Mon, 27 Feb 2012 09:09:28 -0500 Steven Truelove <steven.truelove@utoronto.ca> wrote: > When calling shmget with SHM_HUGETLB, shmget aligns the request size to PAGE_SIZE, but this is not sufficient. Modified hugetlb_file_setup to align requests to the huge page size. > > Signed-off-by: Steven Truelove <steven.truelove@utoronto.ca> > --- > fs/hugetlbfs/inode.c | 9 ++++++--- > 1 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index 1e85a7a..6c23f09 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -938,6 +938,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size, > struct path path; > struct dentry *root; > struct qstr quick_string; > + struct hstate *hstate; > + int num_pages; > > *user = NULL; > if (!hugetlbfs_vfsmount) > @@ -967,10 +969,11 @@ struct file *hugetlb_file_setup(const char *name, size_t size, > if (!inode) > goto out_dentry; > > + hstate = hstate_inode(inode); > + num_pages = (size + huge_page_size(hstate) - 1) >> > + huge_page_shift(hstate); > error = -ENOMEM; > - if (hugetlb_reserve_pages(inode, 0, > - size >> huge_page_shift(hstate_inode(inode)), NULL, > - acctflag)) > + if (hugetlb_reserve_pages(inode, 0, num_pages, NULL, acctflag)) > goto out_inode; > > d_instantiate(path.dentry, inode); A few things... - sys_mmap_pgoff() does the rounding up prior to calling hugetlb_file_setup(). ipc/shm.c:newseg() does not. We should be consistent here: do it in the caller or the callee, not both (or neither!). I guess doing it in the callee would be best. - The above code could/should have used ALIGN(). Or round_up(): the difference presently escapes me, even though it was so obvious that we left all these things undocumented. - What's the point in aligning the length if we don't also look at the start address? If that isn't a multiple of huge_page_size(), we will need an additional page. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] HUGETLBFS: Align memory request to multiple of huge page size to avoid underallocating. 2012-02-27 23:42 ` [PATCH] HUGETLBFS: Align memory request to multiple of huge page size to avoid underallocating Andrew Morton @ 2012-02-28 2:55 ` Steven Truelove 2012-02-28 3:04 ` Andrew Morton 0 siblings, 1 reply; 3+ messages in thread From: Steven Truelove @ 2012-02-28 2:55 UTC (permalink / raw) To: Andrew Morton; +Cc: wli, linux-kernel, linux-mm On 27/02/2012 6:42 PM, Andrew Morton wrote: > On Mon, 27 Feb 2012 09:09:28 -0500 > Steven Truelove<steven.truelove@utoronto.ca> wrote: > >> When calling shmget with SHM_HUGETLB, shmget aligns the request size to PAGE_SIZE, but this is not sufficient. Modified hugetlb_file_setup to align requests to the huge page size. >> >> Signed-off-by: Steven Truelove<steven.truelove@utoronto.ca> >> --- >> fs/hugetlbfs/inode.c | 9 ++++++--- >> 1 files changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c >> index 1e85a7a..6c23f09 100644 >> --- a/fs/hugetlbfs/inode.c >> +++ b/fs/hugetlbfs/inode.c >> @@ -938,6 +938,8 @@ struct file *hugetlb_file_setup(const char *name, size_t size, >> struct path path; >> struct dentry *root; >> struct qstr quick_string; >> + struct hstate *hstate; >> + int num_pages; >> >> *user = NULL; >> if (!hugetlbfs_vfsmount) >> @@ -967,10 +969,11 @@ struct file *hugetlb_file_setup(const char *name, size_t size, >> if (!inode) >> goto out_dentry; >> >> + hstate = hstate_inode(inode); >> + num_pages = (size + huge_page_size(hstate) - 1)>> >> + huge_page_shift(hstate); >> error = -ENOMEM; >> - if (hugetlb_reserve_pages(inode, 0, >> - size>> huge_page_shift(hstate_inode(inode)), NULL, >> - acctflag)) >> + if (hugetlb_reserve_pages(inode, 0, num_pages, NULL, acctflag)) >> goto out_inode; >> >> d_instantiate(path.dentry, inode); > A few things... > > - sys_mmap_pgoff() does the rounding up prior to calling > hugetlb_file_setup(). ipc/shm.c:newseg() does not. > > We should be consistent here: do it in the caller or the callee, > not both (or neither!). I guess doing it in the callee would be > best. > > - The above code could/should have used ALIGN(). Or round_up(): the > difference presently escapes me, even though it was so obvious that > we left all these things undocumented. > > - What's the point in aligning the length if we don't also look at > the start address? If that isn't a multiple of huge_page_size(), we > will need an additional page. > Since mmap has an address to check and shmget does not, if the address is going to be checked it will need to be in the caller. If you like, I will leave the size check in hugetlb_file_setup() and remove the size check from mmap_pgoff, but replace it with a check of the address. That will centralize the common check (size of buffer), and let mmap_pgoff check the part that is unique to it. Patch shortly. Steven Truelove -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] HUGETLBFS: Align memory request to multiple of huge page size to avoid underallocating. 2012-02-28 2:55 ` Steven Truelove @ 2012-02-28 3:04 ` Andrew Morton 0 siblings, 0 replies; 3+ messages in thread From: Andrew Morton @ 2012-02-28 3:04 UTC (permalink / raw) To: Steven Truelove; +Cc: wli, linux-kernel, linux-mm On Mon, 27 Feb 2012 21:55:17 -0500 Steven Truelove <steven.truelove@utoronto.ca> wrote: > > A few things... > > > > - sys_mmap_pgoff() does the rounding up prior to calling > > hugetlb_file_setup(). ipc/shm.c:newseg() does not. > > > > We should be consistent here: do it in the caller or the callee, > > not both (or neither!). I guess doing it in the callee would be > > best. > > > > - The above code could/should have used ALIGN(). Or round_up(): the > > difference presently escapes me, even though it was so obvious that > > we left all these things undocumented. > > > > - What's the point in aligning the length if we don't also look at > > the start address? If that isn't a multiple of huge_page_size(), we > > will need an additional page. > > > > Since mmap has an address to check and shmget does not, if the address > is going to be checked it will need to be in the caller. Or pass a value of 0 from shmget. > If you like, I > will leave the size check in hugetlb_file_setup() and remove the size > check from mmap_pgoff, but replace it with a check of the address. That > will centralize the common check (size of buffer), and let mmap_pgoff > check the part that is unique to it. Patch shortly. > > Steven Truelove -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-02-27 23:42 ` [PATCH] HUGETLBFS: Align memory request to multiple of huge page size to avoid underallocating Andrew Morton
2012-02-28 2:55 ` Steven Truelove
2012-02-28 3:04 ` Andrew Morton
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