Messages in this thread | | | Date | Wed, 27 Jan 2021 19:40:49 +0200 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH v3 3/5] x86/sgx: Optimize the free_cnt count in sgx_epc_section |
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I could bet some money that this does not bring any significant performance gain.
On Sun, Jan 24, 2021 at 02:29:05PM +0800, Tianjia Zhang wrote: > `section->free_cnt` represents the free page in sgx_epc_section, > which is assigned once after initialization. In fact, just after the > initialization is completed, the pages are in the `init_laundry_list` > list and cannot be allocated. This needs to be recovered by EREMOVE > of function sgx_sanitize_section() before it can be used as a page > that can be allocated. The sgx_sanitize_section() will be called in > the kernel thread ksgxd. > > This patch moves the initialization of `section->free_cnt` from the > initialization function `sgx_setup_epc_section()` to the function > `sgx_sanitize_section()`, and then accumulates the count after the
Use single quotes instead of hyphens.
> successful execution of EREMOVE. This seems to be more reasonable, > free_cnt will also truly reflect the allocatable free pages in EPC. > > Sined-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> > Reviewed-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/kernel/cpu/sgx/main.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c > index 4465912174fd..e455ec7b3449 100644 > --- a/arch/x86/kernel/cpu/sgx/main.c > +++ b/arch/x86/kernel/cpu/sgx/main.c > @@ -48,6 +48,7 @@ static void sgx_sanitize_section(struct sgx_epc_section *section) > if (!ret) { > spin_lock(§ion->lock); > list_move(&page->list, §ion->page_list); > + section->free_cnt++; > spin_unlock(§ion->lock);
Someone can try to allocate a page while sanitize process is in progress.
I think it is better to keep critical sections in the form that when you leave from one, the global state is legit.
> } else > list_move_tail(&page->list, &dirty); > @@ -643,7 +644,6 @@ static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, > list_add_tail(§ion->pages[i].list, §ion->init_laundry_list); > } > > - section->free_cnt = nr_pages; > return true; > } > > -- > 2.19.1.3.ge56e4f7 > >
/Jarkko
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